October 7th, 2018

Reloading Tip: Bullet Bearing Surface and Pressure

USAMU Bullet Ogive Comparision Safety Reloading
Photo 1: Three Near-Equal-Weight 7mm Bullets with Different Shapes

TECH TIP: Bullets of the same weight (and caliber) can generate very different pressure levels due to variances in Bearing Surface Length (BSL).

Bullet 1 (L-R), the RN/FB, has a very slight taper and only reaches its full diameter (0.284″) very near the cannelure. This taper is often seen on similar bullets — it helps reduce pressures with good accuracy. The calculated BSL of Bullet 1 was ~0.324″. The BSL of Bullet 2, in the center, was ~0.430”, and Bullet 3’s was ~ 0.463″. Obviously, bullets can be visually deceiving as to BSL!


This article from the USAMU covers an important safety issue — why you should never assume that a “book” load for a particular bullet will be safe with an equal-weight bullet of different shape/design. The shape and bearing surface of the bullet will affect the pressure generated inside the barrel. This is part of the USAMU’s Handloading Hump Day series, published on the USAMU Facebook page.

Beginning Handloading, Part 13:
Extrapolating Beyond Your Data, or … “I Don’t Know, What I Don’t Know!”

We continue our Handloading Safety theme, focusing on not inadvertently exceeding the boundaries of known, safe data. Bullet manufacturers’ loading manuals often display three, four, or more similar-weight bullets grouped together with one set of load recipes. The manufacturer has tested these bullets and developed safe data for that group. However, seeing data in this format can tempt loaders — especially new ones — to think that ALL bullets of a given weight and caliber can interchangeably use the same load data. Actually, not so much.

The researchers ensure their data is safe with the bullet yielding the highest pressure. Thus, all others in that group should produce equal or less pressure, and they are safe using this data.

However, bullet designs include many variables such as different bearing surface lengths, hardness, and even slight variations in diameter. These can occasionally range up to 0.001″ by design. Thus, choosing untested bullets of the same weight and caliber, and using them with data not developed for them can yield excess pressures.

This is only one of the countless reasons not to begin at or very near the highest pressure loads during load development. Always begin at the starting load and look for pressure signs as one increases powder charges.

Bullet bearing surface length (BSL) is often overlooked when considering maximum safe powder charges and pressures. In photo 1 (at top), note the differences in the bullets’ appearance. All three are 7mm, and their maximum weight difference is just five grains. Yet, the traditional round nose, flat base design on the left appears to have much more BSL than the sleeker match bullets. All things being equal, based on appearance, the RN/FB bullet seems likely to reach maximum pressure with significantly less powder than the other two designs.

Bearing Surface Measurement Considerations
Some might be tempted to use a bullet ogive comparator (or two) to measure bullets’ true BSL for comparison’s sake. Unfortunately, comparators don’t typically measure maximum bullet diameter and this approach can be deceiving.

Photo 2: The Perils of Measuring Bearing Surface Length with Comparators
USAMU Bullet Ogive Comparision Safety Reloading

In Photo 2, two 7mm comparators have been installed on a dial caliper in an attempt to measure BSL. Using this approach, the BSLs differed sharply from the original [measurements]. The comparator-measured Bullet 1 BSL was 0.694” vs. 0.324” (original), Bullet 2 was 0.601” (comparator) vs. 0.430” (original), and Bullet 3 (shown in Photo 2) was 0.602” (comparator) vs. 0.463” (original). [Editor’s comment — Note the very large difference for Bullet 1, masking the fact that the true full diameter on this bullet starts very far back.]

Permalink Bullets, Brass, Ammo, Reloading 10 Comments »
October 7th, 2018

Darrell Holland Upgrade for RCBS Bench Priming Tool

Priming Tool Holland Perfect RCBS bench mount primer

Gunsmith Darrell Holland sells a priming tool that upgrades the RCBS Auto Bench Priming Tool with key features — including primer seating depth control. If your hand starts to hurt after priming dozens of cases with a hand-held, squeeze-type priming tool, you may want to consider Holland’s invention, which he calls the “Perfect Primer Seater” (PPS).

Holland basically has modified the RCBS lever, adding a precise crush control and a means of measuring depth with a gauge. He claims this gives “an EXACT primer seating depth based on primer pocket depth and primer thickness”. With Holland’s PPS, primer seating depth is controlled with a rotating wheel that limits lever travel in precise gradations. You can buy the complete priming system for $215.00, or, if you already own the RCBS Auto Prime tool, you can purchase an adapter kit (with base, arm, adjuster, and gauge etc.) for $120.00. To order, visit Hollandguns.com. Click on “Reloading Equipment”, and look for the Perfect Primer Seater. Scroll down to the bottom of the page to add items to the shopping cart.

Priming Tool Holland Perfect RCBS bench mount primer

Priming Tool Holland Perfect RCBS bench mount primerUser Review by Tommy Todd
Sierra Bullets’ Chief Ballistician Tommy Todd acquired the Holland Perfect Primer Seater, and gave it a positive review. Todd writes: “This cartridge case priming system allows you to measure the primer pocket depth and adjust the seating tool to match the primer seating depth for a contact fit with a measured lot of primers to the cases you are working with. Mr. Darrell Holland has taken a standard RCBS automatic bench-mounted priming tool and modified it to a new level of precision. The modifications allow you to measure the primer pocket depth, primer height, and with the addition of an adjustable stop on the priming tool achieve precision primer seating, rather than how the primer ‘feels'[.]

If you are already utilizing the RCBS priming tool, Mr. Holland offers an adapter kit to upgrade your equipment. If you are looking for a new priming unit, I suggest giving this product a try. Increasing consistency when seating primers should result in smaller groups[.]”

Permalink Bullets, Brass, Ammo, Gear Review, Reloading 3 Comments »
October 6th, 2018

Case Prep Tips from Western Powders

Western Powders Case Preparation prep inspection flash holes primer pockets reloading

Western Powders (which sells Accurate, Ramshot, and Norma powders) has published an article on case inspection and preparation. There are many tips in this article that can be useful to precision hand-loaders. For example, every time you open a new box of cartridge brass (particularly from domestic makers), you should inspect each case for flaws.

TIP ONE: Visual Inspection — Finding Flaws
Cases are mass-produced items and malformed ones are relatively common. Inspect each case carefully looking for obvious defects. A bench-mounted magnifying glass with light is a real help for the over-40 crowd. The main defects will be cracks in the neck or case body, crushed shoulders or deep creases in the neck. Next check the primer pocket. It is also fairly common to find flash holes that are damaged or, more rarely, not concentric to the primer pocket.

Western Powders Case Preparation prep inspection flash holes primer pockets reloading

Imperfections like small dings in the case body, or necks that are not completely symmetrical do not have to be eliminated at this step. Damage of this sort is usually from loose packaging and usually has not seriously damaged the brass. [Running an expander mandrel in the neck] and fire-forming will iron out these largely cosmetic issues.

The Western Powder article also talks about primer pocket uniforming. We do NOT normally uniform the pockets for Lapua or RWS brass from the start. However, pocket uniforming can be beneficial with some other brands of brass, including Lake City, Remington, and Winchester. If you shoot milsurp brass, set time aside for pocket uniforming.

TIP TWO: Primer Pocket Uniforming
Western Powders Case Preparation inspection flash holes primer pockets reloadingLike flash holes, primer pockets are mass-produced and prone to small dimensional changes. A uniforming tool is used to make the depth of each primer pocket consistent. In turn this allows similar firing pin strike depths on the primer which creates more consistent ignition characteristics.

A good uniforming tool should have a shoulder, or another positive stop, that sets the cutter’s depth. Its use is pretty straightforward. The cutter is inserted into the pocket and turned clockwise several times until the stop in flush with the case head and no more brass is removed from the juncture of the pocket’s base and sidewall. This a job best done by hand. You will feel when the cutting is finished by a change in how smoothly the cutter turns in the pocket. Very little material is actually removed; usually just enough to square the radius at the bottom of the pocket.


READ Full Case Prep Article in Western Powders Blog »

Western Powders Blog Case Prep Neck turning

Permalink Bullets, Brass, Ammo, Reloading No Comments »
October 5th, 2018

Mount Press ABOVE Your Bench with Bench Topper

Berry's Bench Topper Reloading Platform
Berry’s unique, all-metal Bench Topper lets you place a reloading press above your bench surface, clearing valuable space in your reloading area.

The Bench Topper, from Berry’s Manufacturing, is a sturdy platform that holds a loading press and storage bins in a raised position above your bench — effectively creating additional room for scales, trimmers, and component storage below. The $114.66 Bench Topper (Midsouth item 037-00191) can bolted to your bench, or it can be secured with C-Clamps (for easy removal). Do you load at the range? The Bench Topper can be easily transported in your vehicle, providing a handy platform for your press and powder measure.

Bench Topper Specs:

Top Plate:
6 x 20 x 1/4″

Bottom Plate:
10 x 20 x 1/4″

Height: 11.5 Inches

Weight: 12.5 Pounds

Berry’s Bench Topper is crafted from CNC-machined aluminum and powder-coated black for durability. It comes with two aluminum hangers for storage bins for bullets or brass. All fasteners are recessed for a clean work surface. NOTE: The Bench Topper must be assembled by the purchaser, and YOU MUST DRILL YOUR OWN HOLES for installation of your press or other hardware. This requires a few minutes of initial set-up time, but this allows a secure, custom installation for any brand of reloading press.

Product Tip from EdLongrange. We welcome user submissions.
Permalink Gear Review 2 Comments »
October 2nd, 2018

Bump Control: Precision Shims for Full-Length Sizing Dies

Sinclair Die Shims

When your cases become hard to extract, or you feel a stiff bolt lift when removing a cartridge, it’s probably time to full-length size your cases, and “bump” the shoulder back. With a hunting load, shoulder bumping may only be required every 4-5 loading cycles. Short-range benchrest shooters, running higher pressures, typically full-length size every load cycle, bumping the shoulder .001-.002″. High Power shooters with gas guns generally full-length size every time, and may need to bump the shoulders .003″ or more to ensure reliable feeding and extraction.

Use Shims for Precise Control of Shoulder Bump
Some shooters like to set the “default” position for their full-length die to have an “ample” .003″ or .004″ shoulder bump. When they need less bump, a simple way to reduce the amount of shoulder movement is to use precision shims in .001″ (one-thousandth) increments.

Here are reports from Forum members who use the shims:

“Great product. I have my die lock ring(s) adjusted for the shortest headspace length on my multiple chambers 6BRs and 6PPCs. When needing a longer headspace, I just refer to my notes and add the appropriate shim under the lock ring. Keep it simple.” — F.D. Shuster

Mats Johansson writes: “I’ve been using [shims] since Skip Otto (of BR fame) came out with them. I set up my dies with the .006″ shim, giving me the option of bumping the shoulder a bit more when the brass gets old and hardens while still having room to adjust up for zero headspace, should I have missed the original setup by a thou or two. Hunting rounds can easily be bumped an extra .002-.003″ for positive, no-crush feeding. Being a safety-oriented cheapskate, I couldn’t live without them — they let me reload my cases a gazillion times without dangerous web-stretching. Shims are a must-have, as simple as that.” — Mats Johansson

Sinclair Die ShimsSinclair Int’l offers a seven-piece set of Sizing Die Shims that let you adjust the height of your die (and thereby the amount of bump and sizing) in precise .001″ increments. Sinclair explains: “Some handloaders will set their die up to achieve maximum sizing and then progressively use Sinclair Die Shims between the lock ring and the press head to move the die away from the shellholder. Doing this allows you to leave the lock ring in the same position. These shims are usually available in increments of .001″ and work very well.”

Seven Shims from .003″ to .010″
Sinclair’s Die Shim Kit (item 22400) includes seven shims in thicknesses of .003, .004, .005, .006, .007, .008, and .010. For ease of use, shim thickness is indicated by the number of notches cut in the outer edge of each shim. Even without looking you can “count” the notches by feel. Normally priced at $11.99, this shim kit is on sale now for $10.99.

Permalink Bullets, Brass, Ammo, Reloading 1 Comment »
September 26th, 2018

Safety Tip for Loading With Coated Bullets

Moly Danzac Bullet Coating Anti-friction HBN

Coating bullets with a friction-reducing compound such as Molybdenum Disulfide (Moly) offers potential benefits, including reduced barrel heat, and being able to shoot longer strings of fire between bore cleanings. One of the effects of reduced friction can be the lessening of internal barrel pressures. This, in turn, means that coated bullets may run slower than naked bullets (with charges held equal). To restore velocities, shooters running coated bullets are inclined to “bump up” the load — but you need to be cautious.

Be Careful When Increasing Loads for Coated Bullets
We caution shooters that when your start out with coated bullets in a “fresh barrel” you should NOT immediately raise the charge weight. It may take a couple dozen coated rounds before the anti-friction coating is distributed through the bore, and you really start to see the reduced pressures. Some guys will automatically add a grain or so to recommended “naked” bullet charge weights when they shoot coated bullets. That’s a risky undertaking.

We recommend that you use “naked” bullet loads for the first dozen coated rounds through a new barrel. Use a chronograph and monitor velocities. It may take up to 30 rounds before you see a reduction in velocity of 30-50 fps that indicates that your anti-friction coating is fully effective.

We have a friend who was recently testing moly-coated 6mm bullets in a 6-6.5×47. Moly had not been used in the barrel before. Our friend had added a grain to his “naked” bullet load, thinking that would compensate for the predicted lower pressures. What he found instead was that his loads were WAY too hot initially. It took 30+ moly-coated rounds through the bore before he saw his velocities drop — a sign that the pressure had lowered due to the moly. For the rounds fired before that point his pressures were too high, and he ended up tossing some expensive Lapua brass into the trash because the primer pockets had expanded excessively.

LESSON: Start low, even with coated bullets. Don’t increase your charge weights (over naked bullet loads) until you have clear evidence of lower pressure and reduced velocity.

Procedure After Barrel Cleaning
If you shoot Moly, and clean the barrel aggressively after a match, you may want to shoot a dozen coated “foulers” before starting your record string. Robert Whitley, who has used Moly in some of his rifles, tells us he liked to have 10-15 coated rounds through the bore before commencing record fire. In a “squeaky-clean” bore, you won’t get the full “benefits” of moly immediately.

To learn more about the properties of dry lubricants for bullets, read our Guide to Coating Bullets. This covers the three most popular bullet coatings: Molybdenum Disulfide (Moly), Tungsten Disulfide (WS2 or ‘Danzac’), and Hexagonal Boron Nitride (HBN). The article discusses the pros and cons of the different bullet coatings and offers step-by-step, illustrated instructions on how to coat your bullets using a tumbler.

Permalink Reloading, Tech Tip 3 Comments »
September 24th, 2018

Bargain Finder 157: AccurateShooter’s Deals of the Week

Accurateshooter Bargain Finder Deals of Week

At the request of our readers, we provide select “Deals of the Week”. Every Monday morning we offer our Best Bargain selections. Here are some of the best deals on firearms, hardware, reloading components, optics, and shooting accessories. Be aware that sale prices are subject to change, and once clearance inventory is sold, it’s gone for good. You snooze you lose.

1. Natchez — Rock Chucker Supreme Reloading Kit, $279.99

Deals of Week RCBS Rock Chucker Supreme Kit

Everything you see above can be yours for just $279.99. Great Deal. Right now, Natchez is selling the Rock Chucker Supreme Master Reloading Kit for $279.99, a great price considering all the hardware you get: Press, Primer Tool, Scale, Powder Measure, Loading Tray, Reloading Manual and more. Heck, the Rock Chucker press alone is worth $160.00+. This is good starter kit for any reloader with sturdy items (like the Rock Chucker press), that will last a lifetime.

2. Natchez — FREE HazMat on Orders of $99.99 or more

Here’s a very attractive promotion if you need powder and/or primers. Right now Natchez is offering FREE HazMat for orders of $99.99 or more. This can save you $25-$40 on the delivered cost of your order. NOTE: Act soon — this deal expires 9/26/2018 at 11:59 PM and you must use CODE FH180924.

Credit EdLongrange for this tip. He notes: “Natchez … was somewhat vague as to whether you need to get $99.99 of the same product, so I added one each of two different primers and two different powders and the code worked. Natchez has … excellent prices on Federal Gold Medal Match primers, including what used to be really-hard-to-get GM215M.” ORDER HERE.

3. Brownells — Howa .308 Win Full Camo with Scope $652.99

Brownells Howa Hunting rifle kryptec Camo Nikko scope bargain deal hydrodipped

The Howa 1500 Full-Dip Kryptek rifle is purpose-built for hunters who want a full matching camo rifle and scope. This .308 Winchester rig features a pillar-bedded Howa action with 20″ barrel in a quality Hogue stock. On top is a Nikko 4-16x44mm scope with one-inch tube. The entire rifle and scope features a hydro-dipped Kryptek Highlander camo finish which is handsome AND very effective in the field. NOTE: The current Sale Price is $662.99. Use CODE M8Y to save $10 and get FREE Shipping. That lowers your delivered price to $652.99, which includes the Nikko 4-16X scope. All-up weight, with scope, is 10 pounds. Sorry this deal is not currently available in other chamberings — .308 Win only.

4. Amazon — Nikon FX1000 6-24x56mm SFP Scope, $599.99

Amazon nikon X1000 Black scope MOA Mrad SFP second focal plane

We’ve checked out the Nikon Black X1000 series scopes and they offer a lot of performance for the price. On sale now at Amazon for just $599.99 is the second focal plane (SFP) BLACK X1000 6-24x50mm model with X-MOA reticle. A Mil version with 0.1 Mil click and X-MRAD reticle is also available for $646.99. These scopes have very crisp controls and great glass for the money. The MOA version 1/4-MOA click with 12 MOA per revolution and 60 total MOA internal adjustment. The Mil version has 0.1 MilRad clicks with 17 total MRAD internal adjustment travel. On both versions, a side-mounted control offer 10 intensity levels of red illumination.

5. CDNN Holster Sale — Huge Savings — Everything Under $20.00

CDNN Holster deal bargain sale

Currently, CDNN is running a great Holster Liquidation Sale. Every holster in stock is just $19.99, including some models that normally retail for over $85.00. Chose from quality polymer holsters or traditional leather holsters from Mitch Rosen. Many of these holsters are designed for Sig Sauer pistols, but there are holsters for other popular pistol brands as well.

6. Amazon — Plano 52″ Double Rifle Case with Wheels, $109.08

Plano double scoped rifle case with wheels

This Plano Double Scoped Rifle Case is an Amazon Best Seller for good reason. It offers the functionality and durability of an SKB-type hard case for HALF the money. This is under $110.00, while the equivalent SKB is around $240.00, so you can buy two Planos for the price of one SKB. The 51.5″ interior will fit most scoped competition rifles up to about 29″ barrels (measure your own rifle to make sure). If you separate the barreled action from the stock you can transport even ultra-long ELR rifles. The handles are convenient and beefy and the wheels make this case easy to move. This is a very tough, roomy case for the money (plus there’s Free Shipping).

7. Midsouth — Hornady LnL Auto Charge Scale/Dispenser, $158.99

Hornady Lock and load auto charge scale powder dispenser sale discount

The Hornady Lock N Load Auto Charge Electronic Scale/Dispenser is now on sale for just $158.99 at Midsouth Shooters Supply, discounted way down from the regular $226.24 price. That’s the lowest price we’ve seen on this product in a long time, making this a real bargain. If you are looking for an affordable combination digital scale and powder dispenser, this is very attractive pricing. By comparison, the new RCBS ChargeMaster Lite sells for around $250.00 and is back-ordered at most vendors. That means you can save at least $90.00 by buying RED instead of GREEN.

8. Amazon — Neiko Digital Calipers, $16.85

Amazon Neiko Digital Caliper

Even if you have a good set of calipers, you may want to get one of these Neiko 01407A Digital Calipers. The #1 best-selling digital caliper on Amazon.com, this Neiko tool features a large LCD Screen and measures up to 6.0 inches. With over 3000 customer reviews, this product has earned an overall rating of 4.4 out of 5 stars. It’s hard to go wrong for $16.85, even if you just use these as a spare set for measuring group sizes and case trim lengths.

Permalink Bullets, Brass, Ammo, Hot Deals, Optics 1 Comment »
September 18th, 2018

‘Quit Neck Sizing’ — Cortina Explains Full-Length Sizing is Better

Full-Length Sizing Erik Cortina Neck Sizing Video

Our friend Erik Cortina is at Raton, NM this week at the F-Class Nationals. When he’s not shooting (or working) Erik produces YouTube videos. One of his most popular videos explained why you should full-length size cartridge brass. In no uncertain terms Erik says: “Quit Neck Sizing!!!” Watch the Video:

Why It’s Smart to Full-Length Size Your Brass

Commentary by Erik Cortina

Should You Full-Length Size Your Cartridge Brass?

Absolutely. Let Me Explain Why…

I have seen it time and time again, shooters on the line wrestling with their rifle trying to get the bolt closed while the wind is switching. They were too focused trying to get their bolt to close and getting their rifle settled back on the bags that they missed the wind switch. Bang… Eight! The straw that broke the camel’s back for me was at the 2017 Canadian Nationals. I was paired up with a young girl and she would try really hard to close the bolt on her rifle. The majority of the time she would get it to close, but often times she could not even get the round to chamber. She was focused on her rifle the entire time rather than on the conditions. When we completed our strings, she had five rounds that did not chamber our of 15! That is way too many!. I told her she needed to think about Full-length sizing with 0.002″ shoulder bump, or Controlled Full-length Sizing like I call it. I told her not to worry about losing accuracy. I told her that I full-length size all my rounds and asked if she noticed how smooth my bolt was and noticed my score. She said yes, they were both great!

Full-Length Sizing Erik Cortina Neck Sizing Video

Controlled Full-length Sizing Does NOT Harm Accuracy
I have found that Controlled Full-length Sizing does NOT hurt accuracy or shorten brass life. I find that I can focus much more on the conditions when I don’t have to think about chambering a round nor extracting it. It has become second nature. After firing, I keep my head welded to the stock, I open the bolt by placing my thumb on top of stock and rotating hand upwards. I reach in and retrieve spent case, place it back in ammo box, and pick up another loaded round and put in chamber. I verify conditions and when ready, I push the bolt in and close it with my index and middle finger.

With Controlled Full-length Sizing you “bump” the shoulder around .002″ for bolt guns.*
full length sizing
Image courtesy Sinclair International which carries a variety of Full-length dies.

Whidden Gunworks DiesWhidden Full-Length Sizing Dies
by AccurateShooter.com Editor
For proper Full-length sizing, you want a quality die that’s a very good match to your chamber. For our project rifles we usually turn to Whidden Gunworks which offers both bushing and non-bushing FL dies. And if you want the hot new option, check out Whidden’s patent-pending, click-adjustable FL-sizing die. This gives instant, precise control over shoulder bump. It works great.

*With gas guns, such as the AR10, you may want to increase shoulder bump to .003″ or more. With some benchrest cartridges, .0015″ bump may prove optimal. But .002″ is a good starting point.

Permalink - Videos, Bullets, Brass, Ammo, Reloading 1 Comment »
September 7th, 2018

TIP: Polish Seating Stems to Eliminate Ring Marks on Bullets

Seating Stem Reloading Tip Sierra Bullet .223 Remington compressed loads

Here’s a helpful hint for hand-loaders from Sierra Bullets. While this article focuses on Sierra’s new Tipped Match-King bullets, the recommended solutions apply to other bullet types as well. The article explains how sharp edges on a seating stem can cause a ring to be pressed into the bullet jacket — especially with compressed loads that resist downward bullet movement. Here Sierra technician Rich Machholz diagnoses the problem and provides a solution.

Seating Stem Reloading Tip Sierra Bullet .223 Remington compressed loads

Solutions for Ring Marks Caused by Seating Stems

by Sierra Bullets Ballistic Technician Rich Machholz
Now that the new Tipped MatchKing® (TMK) bullets are being shipped and shooters are putting them to use I have received several calls regarding marking on the bullet ogive from the seating stem.

The cause can be traced to one of several things. In the .223 and especially with the long, 77 grain TMK seated at 2.250” or even 2.260” most loads of Varget® and Reloder® 15 are compressed loads, sometimes heavily compressed. This puts a great deal of pressure on the bullet through the seating stem. The result of all this pressure is a mark of varying depth and appearance on the ogive of the bullet. [Editor: We have seen this issue with a variety of other bullet types/shapes as well, including non-tipped VLDs. The solution is profiling the internal cone of the seating stem to match your bullet shape.]

Some older seating stems might even bear against the tip of the bullet which can make a slight bulge in the jacket just below the junction of the resin tip and the copper jacket in a compressed load. If this is the case there is not a ready fix other than calling the die manufacturer and requesting a new deeper seating stem.

Polish Your Seating Stem to Remove Sharp Internal Edges
If the seating stem is of proper depth the culprit most generally is a thin sharp edge on the inside taper of the seating stem. This is an easy fix that can be accomplished by chucking a spare 77 grain bullet in your drill, coating it with valve grinding compound or even rubbing compound or in a pinch even tooth paste.* Remove the seating stem assembly from the seating die. Turn the drill on and put the seating stem recess over the spinning bullet with the polishing compound to break or smooth the sharp edge that is making the offending mark. This might take more than one application to get the proper polish depending upon what you use, but the more you polish the better the blend of angles which will [ensure the stem matches the bullet contours, not leaving a sharp ring].

If the above is a little more than you care to tackle you might try very fine emery cloth twisted to a point that can be inserted into the mouth to the seating stem and rotated to polish the inside to eliminate any sharp edges that might be present.

Load Advice for 77gr TMKs in the .223 Rem
And last but certainly not least. Actually, even though we don’t say you need additional data for the TMKs, remember you are dealing with heavily-compressed loads in some cases because of the additional bullet length. Due to the additional length of these new bullets and in the interest of gaining some room in the case you might consider trying a slightly faster extruded powder like BenchMark or the 4895s or an even more dense powder like the spherical H335®, CFE223 or TAC. The extra room will allow for trouble free bullet seating also.

Good luck and remember we are no further away than your telephone: 1-800-223-8799.

Sierra Bullets Match-King Reloading Bullet Seating

Permalink Bullets, Brass, Ammo, Reloading, Tech Tip 5 Comments »
August 31st, 2018

Cartridge Base to Ogive (CBTO) Length — Factors to Consider

chamber length loading berger bullets
Here are two different bullet types, seated to the same CBTO length, but different COAL. Note the shiny scratches on the bullets made by the comparator tool which indicates a point on the bullet ogive near where the ogive will engage the rifling.

Berger Bullets COAL length cartridgeEffects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 2
by Bryan Litz for Berger Bullets.
Part One of this series focused on the importance of COAL in terms of SAAMI standards, magazine lengths, seating depths, and pressure levels. Another measure of length for loaded ammunition is highly important to precision, namely Cartridge Base to Bullet Ogive Length (CBTO).

Figure 2. Chamber throat geometry showing the bullet jump to the rifling or lands.
chamber length loading berger bullets

Look at Figure 2. Suppose the bullet was seated out of the case to the point where the base of the bullet’s nose (ogive) just contacted the beginning of the riflings (the lands) when the bolt was closed. This bullet seating configuration is referred to as touching the lands, or touching the riflings and is a very important measurement to understand for precision hand-loading. Due to the complex dynamics of internal ballistics which happen in the blink of an eye, the distance a bullet moves out of the case before it engages the riflings is highly critical to precision potential. Therefore, in order to systematically optimize the precision of his handloads, it’s critically important that the precision hand-loader understands how to alter bullet seating depth in relation to the barrel rifling. Part of the required knowledge is understanding how to accurately and repeatably measure the Cartridge Base To Ogive (CBTO) dimension. This is explained in the FULL ARTICLE.

Bryan Litz offers an extended discussion on how to measure CBTO using different tools and methods, including the Hornady OAL gauge. You can read this discussion in the full article found on the Berger Bullets website. CLICK HERE to Read Full Article.

Why Not Use CBTO as a SAAMI Standard?
If CBTO is so important to rifle accuracy, you might ask, “Why is it not listed as the SAAMI spec standard in addition to COAL?” There is one primary reason why it is not listed in the standard. This is the lack of uniformity in bullet nose shapes and measuring devices used to determine CBTO.

Benefits of Having a Uniform CBTO
There is another aspect to knowing your CBTO when checking your COAL as it pertains to performance. With good bullets, tooling, and carefully-prepared cases you can easily achieve a CBTO that varies less than +/- .001″ but your COAL can vary as much as .025″ extreme spread (or more with other brands). This is not necessarily bad and it is much better than the other way around. If you have a CBTO dimension that varies but your COAL dimension is tight (within +/- .002″) then it is most likely that your bullet is bottoming out inside the seater cone on the bullet tip. This is very bad and is to be avoided. It is normal for bullets to have precisely the same nose shape and it is also normal for these same bullets to have nose lengths that can vary as much as .025″.

Summary of Cartridge Base To Ogive (CBTO) Discussion
Here are four important considerations regarding bullet seating depth as it relates to CBTO:

1. CBTO is a critical measurement to understand for handloaders because it’s directly related to precision potential, and you control it by simply setting bullet seating depth.

2. Tools and methods for measuring CBTO vary. Most of the measurement techniques have pitfalls (which may give rise to inconsistent results) that you should understand before starting out.

3. A CBTO that produces the best precision in your rifle may not produce the best precision in someone else’s rifle. Even if you have the same rifle, same bullets, same model of comparator gauges, etc. It’s possible that the gauges are not actually the same, and measurements from one don’t translate to the same dimension for another.

4. Once you find the CBTO that produces the best precision in your rifle, it’s important to allow minimal variation in that dimension when producing quality handloads. This is achieved by using quality bullets, tooling, and properly preparing case mouths and necks for consistent seating.

CLICK HERE to Read Full Article with More Info
Article sourced by EdLongrange. We welcome tips from readers.
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August 28th, 2018

UltimateReloader Video Demonstrates Pistol Case Gauges

Pistol Cartridge Gage Gauge ulimatereloader.com

If you load pistol ammo you should have a case gauge (aka “gage”) for each cartridge type you reload. Caliber-specific, precision-machined cylindrical gauges perform many important functions. They will instantly reveal if your rounds are too long or have excessive headspace. They will also show if your case is bulged or otherwise too fat to chamber easily. You can use the gauge with sized brass as well as loaded rounds.

Case gauges are a “must-have” for anyone loading handgun ammunition, particularly if you crank out large quantities of pistol ammo with a progressive press. An oversize round can cause a misfeed, jam, or other problem. That can ruin your day if you are in the middle of a shooting match. If you are relying on your handgun for self-defense, the last thing you want is a malfunction of any kind. This Editor personally runs every pistol round through a gauge before it goes into the ammo box.

UltimateReloader.com Video Shows How to Use Pistol Case Gauges:

Our friend Gavin Gear of UltimateReloader.com has prepared an excellent video that explains the benefits of pistol case gauges and shows how to use them. Gavin uses the quality gages produced by L.E. Wilson. These are available for the most popular handgun cartridges, both autoloader cartridges, and rimmed revolver cartridges. Gavin demonstrates gage use with .40 SW and .44 magnum cases.

READ Pistol Case Gage ‘How-To’ Guide on UltimateReloader.com

Gavin states: “Using a case gage is very simple, and I would recommend that you add one of these gages to your reloader’s tool chest for each of the pistol cartridge types you reload. It may just save you a lot of time and hassle. Peace of mind is hard to put a price on!”

Ulimate Reloader.com also covers the use of case gauges for rifle cartridges. Rifle cartridge gauges are especially useful in detecting headspace problems. Case gauges can avert many problems, particularly if you reload milsurp rifle brass. CLICK HERE for Rifle Case Gauge “How To” and Video.

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August 26th, 2018

Cartridge Brass Wisdom for Semi-Auto Shooters by Zediker

Glen Zediker reloaders corner midsouth book AR-16 reloading semi-auto brass safety primer resizing

Here are highlights from an article Glen Zediker wrote for the Midsouth Blog. In this article Glen focuses on cartridge brass for semi-auto rifles, AR-platform guns in particular. Glen notes that semi-autos are tougher on brass than bolt-action rifles, so you need strong, durable brass, that has been full-length sized. And you need to be careful about neck tension, and primers. The article starts with Glen’s recommendations for tough, hard brass, and then includes the points outlined below.

Glen is the author of many excellent books on reloading. This article is adapted from Glen’s books, Handloading For Competition and Top-Grade Ammo, available at Midsouth HERE. For more information about other books by Glen, visit ZedikerPublishing.com.

Handloading for Competition
by Glen Zediker

The Competitive AR-15
by Glen Zediker

Top-Grade Ammo
by Glen Zediker

ONE: Full Length-Size Cases with Adequate Shoulder Set-Back

This is a huge source of debate… amongst my readers, but, since now I’m strictly speaking of semi-auto needs I doubt there will be much dissent: full-length resize all cases! Most cases from most semi-autos will emerge with a pretty well-blown case shoulder [taming down an excessively functioning gas system can reduce this]. Make double-sure you’re sizing the cases down to at least 0.003 clearance. If you don’t there are safety and function problems ahead.

TWO: USE Sufficient Neck Tension

The case neck [must be] reduced an adequate amount to retain the bullet. There should be a minimum net difference of 0.003 inches (three-thousandths) between sized outside case neck diameter and loaded round outside case neck diameter. [Editor — that means at least three thou of “grip”.] Reason: don’t take a chance of inadvertent bullet movement during the recoil and feeding cycles. That movement can be back or forward! It’s easily possible for a bullet to jump ahead when the inertia from the bolt carrier assembly chambers the next round.

Glen Zediker reloaders corner midsouth book AR-16 reloading semi-auto brass safety primer resizing

THREE: Use Tough Primers

Choose a tough primer! There’s a floating firing pin on an AR15 (M1A also) that is supposed to be held in check but that system doesn’t always work! If you load and extract a round and see a little dimple in the primer, that’s from the firing pin tapping off of it (again, created by inertia of bolt closing). A combination of a high primer and a sensitive primer cup assembly can create a “slam-fire”. Brands? CCI has some mil-spec primers that work well, and I’ve had great success with Remington 7-1/2. Some of the well-respected “match” primers are a little thin. The CCI and Remington also hold up well to the (sometimes) greater firing forces working on the primer (again, from the quick unlocking).

Here’s what I use from Midsouth.

FOUR: Be Sure to Seat Primers Below Flush

And, finally, make double-sure that each and every primer is seated to below flush with the case head! That’s true for any firearm (because it also means that the primer is fully seated) but imperative for safety in a semi-auto. This is especially an issue for those who use a progressive-type loading press.

Permalink Bullets, Brass, Ammo, Competition, Reloading 1 Comment »
August 19th, 2018

Hodgdon Reloading Data Center — Good Place to Start

Hodgdon Reloading data Center hand loading powder

Hodgdon Reloading data Center hand loading powderLooking for a good load for a new rifle? Or perhaps you want to try a new powder and bullet combo for an existing rig. One of the best places to start for load data is Hodgdon’s online Reloading Data Center for pistol, rifle, and shotgun reloaders. Check out the enhanced Data Center at www.HodgdonReloading.com.

In the Data Center, you’ll find thousands of load recipes for pistol, rifle, and shotgun. Rifle shooters will find dozens of loads for their favorite Hodgdon, IMR, and Winchester powders such as H4198, Varget, H4350, and IMR 8208 XBR. And Hodgdon’s Reloading Center is “mobile-friendly” so it works well with smartphones and tables. Navigation is easy, and you can set the search criteria easily choosing your favorite powder or bullets. After choosing a cartridge, you can pre-select specific bullet weights and powder types. That quickly delivers just the information you want and need. You won’t have to scroll through scores of entries for bullets or powders you don’t use.

Hodgdon Reloading data Center hand loading powder

Mobile users will notice that the updated/enhanced Reloading Center is much more “user-friendly” for smart-phone and tablet users. Controls have been optimized for touch-screens, and buttons are large and easy to use. Likewise the results are displayed in a large, easy-to read format.

Hodgdon tip from EdLongrange. We welcome reader submissions.
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July 31st, 2018

Eyeball Your Brass — How to Diagnose Flawed Cases

Case Diagnostics 101 Sierra Bullets .223 Rem 5.56 brass cartridge safety

Ever wondered what caused a particular bulge or marking on a case? And more importantly, does the issue make the case unsafe for further use? Sierra Bullets Ballistic Technician Duane Siercks offers some insight into various issues and their causes in this article from the Sierra Blog.

Incipient Case-Head Separation
This is a Winchester .308 Win case that has a real issue. This case has a very obvious incipient case head separation in the process of becoming a complete failure.

Sierra Case reloading pressure safety inspection

This is most commonly caused by over-sizing the case causing there to be excess headspace on the case. After a few firings and subsequent re-sizing, this case is just about ready to come completely apart. Proper die adjustment is certainly a requirement here. Of course this case is not safe to reuse.

Excessive Pressure (Load Too Hot)
If you will notice in the picture of the case rim, there are two pressure signs to notice. First, look at the primer. It is basically flattened to about the max of what could be considered safe. If this was the only pressure sign noted, I would probably be fine with this load, but would constantly keep an eye on it especially if I was going to use this load in warmer temperatures. This load could easily cross into the “excess pressure” realm very quickly.

Sierra Case reloading pressure safety inspection

There is another sign of pressure that we cannot ignore. If you’ll notice, there is an ejector mark apparent that is located over the “R” of the R-P headstamp. This absolutely tells us that this load would not have been in the safe pressure range. If there were any of these rounds loaded, they should not be fired and should be dis-assembled. This case should not be reloaded.

Split Case-Neck
Here we have an R-P .22-250 case that has died the death. Everything looks fine with this case except the neck is split. This case must be tossed.

Sierra Case reloading pressure safety inspection

A split neck is a normal occurrence that you must watch for. It is caused by work-hardening of the brass. Brass cases get harder with age and use. Brand new cases that are stored for a period of time can become hard enough that they will split like this case within one to two firings. I have had new factory loads do the same thing. Then as we resize and fire these cases repeatedly, they tend to get harder and harder. Eventually they will split. The life of the case can be extended by careful annealing practices. This is an issue that would need to be addressed in an article by itself. Of course this case is no longer usable.

In the classes that I teach, I try to use examples like this to let the students see what they should be looking for. As always, if we can assist you, whether you are new to reloading or very experienced, contact us here at Sierra Bullets by phone at 1-800-223-8799 or by email at sierra@sierrabullets.com.

Dented Case Body
Here we have a Lake City 7.62×51 (.308 Win.) case with two heavy marks/dents in the case body.

Sierra Case reloading pressure safety inspection

This one may be a bit of a mystery. It appears as if this case may have been caught in the action of a semi-auto rifle when the firearm jammed or the case failed to clear during the cycling process. I probably would not reload this case just to prevent any feeding problems. This also appeared to be a factory loaded round and I don’t really see any pressure issues or damage to the case.

CLICK HERE for MORE .223 Rem Case Examples in Sierra Blog

It is very important to observe and inspect your cases before each reloading. After awhile it becomes second nature to notice the little things. Never get complacent as you become more familiar with the reloading process. If ever in doubt, call Sierra’s Techs at 1-800-223-8799.

Sierra Bullets Case Diagnostics Blog

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July 31st, 2018

Reloder 23 and Reloder 26 — Good for Magnum Cartridges

Alliant Bofors Nitrochemie Reloader Reloading RL Reloder powder 22 23 25 26

Do you shoot a magnum cartridge? Here are two modern-formulation powders you may want to try: Reloder 23 and 26. We have been particularly impressed with Reloder 23. It has worked well in competition for target cartridges such as the 7mm RSAUM. Reloder 23 is like a slower version of Reloder 16 — a very temp-stable powder which has proven a worthy rival to H4350.

Ever heard of Alliant Reloder 23? Or Reloder 26? These two relatively new European-produced Reloder propellants were introduced in 2014. Most folks haven’t tried these Reloder powders because it took quite a while for the first shipments of RL 23 and RL 26 to arrive in the USA. But now these two new propellants are available in the USA, with substantial inventories in stock at some larger vendors. For example, Powder Valley has both RL 23 and RL 26 in stock now at $23.50 per pound. Many other vendors have ample RL 23, but RL 26 is a bit harder to find.

From our Forum members who shoot large magnum cartridge types with heavy bullets, we have heard good things about both RL 23 and RL 26. Reports from the field indicate that both these powders are delivering impressive velocities with low velocity ES/SD.

What are the characteristics of RL 23 and RL 26? That question was answered by Paul Furrier who works for ATK, the parent company of Alliant Powders. Posting in our Shooters’ Forum, Paul writes:

“Let me provide some factual info about these products. Some of the stuff that gets propagated is not correct. Reloder 23 is produced by our Swedish partner Bofors, and Reloder 26 is produced in Switzerland by our extremely capable partner Nitrochemie. I have seen it stated that they are both made by Bofors, so that is incorrect.

I have also noticed people are equating Reloder 23 to Reloder 22, and Reloder 26 to Reloder 25. Both of those statements are definitely incorrect. We do state that the performance of Reloder 23 is similar to Reloder 22, and it is, in general burn speed terms, but they are most certainly not the same. We have worked quite a lot of recipes for Reloder 23, and they are not the same as Reloder 22. Reloder 26 is definitely slower burning than Reloder 25, so there shouldn’t be any confusion there either.”

Alliant Bofors Nitrochemie Reloader Reloading RL Reloder powder 22 23 25 26

Furrier says that RL 23 is NOT sensitive to temperature shifts: “Reloder 23 was developed to bring a truly temp-stable powder to the Reloder 22 burn-speed range using Bofors new process technology. This is the second product developed for us with this TZ® process, the first being AR-Comp™. We see terrific efficiencies, SDs, accuracy and flat temp response from these powders. Please try them, I think you will be impressed.”

(more…)

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July 24th, 2018

Doh! Make Sure Your Ammo Fits Your Chamber!

Ruptured Cartridge Case

If you don’t match your ammo to your chamber, bad things can happen, that’s for sure. A while back, Forum member BigBlack had an experience at the gun range that reminds us of the importance of safety when shooting. He encountered evidence that someone had fired the wrong cartridge in a 7mm WSM rifle. The problem is more common than you may think. This Editor has personally seen novices try to shoot 9mm ammo in 40sw pistols. BigBlack’s story is along those lines, though the results were much more dramatic. It’s too bad a knowledgeable shooter was not nearby to “intervene” before this fellow chambered the wrong ammo.

7mm-08 is Not the Same as a 7mm WSM
BigBlack writes: “I know this has probably been replayed a thousand times but I feel we can never be reminded enough about safety. This weekend at the range I found a ruptured case on the ground. My immediate thoughts were that it was a hot load, but the neck area was begging for me to take a closer look, so I did. I took home the exploded case and rummaged through my old cases until I found a close match. From my investigative work it appears someone shot a 7mm-08 in a 7mm WSM. Take a look. In the above photo I’ve put together a 7mm WSM case (top), the ruptured case (middle), and a 7mm-08 case (bottom).”

The photo reveals what probably happened to the 7mm-08 case. The shoulder moved forward to match the 7mm WSM profile. The sidewalls of the case expanded outward in the much larger 7mm WSM chamber until they lacked the strength to contain the charge, and then the case sides ruptured catastrophically. A blow-out of this kind can be very dangerous, as the expanding gasses may not be completely contained within the action.

Can’t Happen to You? Think Again.
This kind of mistake — chambering the wrong cartridge — can happen to any shooter who is distracted, who places even a single wrong round in an ammo box, or who has two types of ammo on the bench. One of our Forum members was testing two different rifles recently and he picked up the wrong cartridge from the bench. As a result, he fired a .30-06 round in a .300 Win Mag chamber, and the case blew out. Here is his story:

“I took two of my hunting rifles I have not used for over 25 years to the range yesterday to get new scopes on paper, a .30-06 and .300 Win Mag. I had four boxes of old Winchester factory ammo (two of each cartridge), which had near identical appearances. I accidentally chambered a .30-06 round in the Sako .300 Win Mag rifle. It sprayed powder on my face and cracked the stock at the pistol grip. If I had not been wearing safety glasses I might be blind right now.

Safety eyewear glasses
You should always wear protective eyewear, EVERY time you shoot.

“I feel lucky and am very thankful for being OK — other than my face looks funny right now. I am also grateful for learning a valuable lesson. I will never put two different cartridges on the bench at the same time again.”

READ More about this incident in our Shooters’ Forum.

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July 20th, 2018

Try Rotating Cases During Bullet Seating to Reduce Run-Out

Bullet Seating Reloading rotate cartridge Run-out TIR

Here is a simple technique that can potentially help you load straighter ammo, with less run-out (as measured on the bullet). This procedure costs nothing and adds only a few seconds to the time needed to load a cartridge. Next time you’re loading ammo with a threaded (screw-in) seating die, try seating the bullet in two stages. Run the cartridge up in the seating die just enough to seat the bullet half way. Then lower the cartridge and rotate it 180° in the shell-holder. Now raise the cartridge up into the die again and finish seating the bullet.

Steve, aka “Short Range”, one of our Forum members, recently inquired about run-out apparently caused by his bullet-seating process. Steve’s 30BR cases were coming out of his neck-sizer with good concentricity, but the run-out nearly doubled after he seated the bullets. At the suggestion of other Forum members, Steve tried the process of rotating his cartridge while seating his bullet. Steve then measured run-out on his loaded rounds. To his surprise there was a noticeable reduction in run-out on the cases which had been rotated during seating. Steve explains: “For the rounds that I loaded yesterday, I seated the bullet half-way, and turned the round 180 degrees, and finished seating the bullet. That reduced the bullet runout by almost half on most rounds compared to the measurements from the first test.”

READ Bullet Seating Forum Thread »

run-out bullet

run-out bullet

Steve recorded run-out measurements on his 30BR brass using both the conventional (one-pass) seating procedure, as well as the two-stage (with 180° rotation) method. Steve’s measurements are collected in the two charts above. As you can see, the run-out was less for the rounds which were rotated during seating. Note, the change is pretty small (less than .001″ on average), but every little bit helps in the accuracy game. If you use a threaded (screw-in) seating die, you might try this two-stage bullet-seating method. Rotating your case in the middle of the seating process won’t cost you a penny, and it just might produce straighter ammo (nothing is guaranteed). If you do NOT see any improvement on the target, you can always go back to seating your bullets in one pass. READ Forum Thread..

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July 15th, 2018

How Ammo Temp Affects Pressure, Velocity, and Point of Impact

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold
In this .308 Win test, 70° F ammo shot 96 FPS slower than ammo heated to 130.5° F. And the 130.5° ammo was 145 fps faster than ammo right out of the freezer (at 25.5° F). That’s a huge difference…

EDITOR’s NOTE: The Sierra tester does not reveal the brand of powder tested here. Some powders are much more temp sensitive than others. Accordingly, you cannot extrapolate test results from one propellant to another. Nonetheless, it is interesting to see the actual recorded velocity shift with ammo temperature variations in a .308 Win.

Written by Sierra Chief Ballistician Tommy Todd
This story originally appeared in the Sierra Bullets Blog
A few weeks ago I was attending the Missouri State F-Class Match. This was a two-day event during the summer and temperatures were hot one day and hotter the next. I shot next to a gentleman who was relatively new to the sport. He was shooting a basically factory rifle and was enjoying himself with the exception that his scores were not as good as he hoped they would be and he was experiencing pressure issues with his ammunition. I noticed that he was having to force the bolt open on a couple of rounds. During a break, I visited with him and offered a couple of suggestions which helped his situation somewhat and he was able to finish the match without major issues.

He was shooting factory ammunition, which is normally loaded to upper levels of allowable pressures. While this ammunition showed no problems during “normal” testing, it was definitely showing issues during a 20-round string of fire in the temperatures we were competing in. My first suggestion was that he keep his ammunition out of the direct sun and shade it as much as possible. My second suggestion was to not close the bolt on a cartridge until he was ready to fire. He had his ammo in the direct sunlight and was chambering a round while waiting on the target to be pulled and scored which can take from a few seconds to almost a minute sometimes.

This time frame allowed the bullet and powder to absorb chamber [heat] and build pressure/velocity above normal conditions. Making my recommended changes lowered the pressures enough for the rifle and cartridge to function normally.

Testing Effects of Ammunition Temperature on Velocity and POI
After thinking about this situation, I decided to perform a test in the Sierra Bullets underground range to see what temperature changes will do to a rifle/cartridge combination. I acquired thirty consecutive .30 caliber 175 grain MatchKing bullets #2275 right off one of our bullet assembly presses and loaded them into .308 Winchester ammunition. I utilized an unnamed powder manufacturer’s product that is appropriate for the .308 Winchester cartridge. This load is not at the maximum for this cartridge, but it gives consistent velocities and accuracy for testing.

I took ten of the cartridges and placed them in a freezer to condition.

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold

I set ten of them on my loading bench, and since it was cool and cloudy the day I performed this test I utilized a floodlight and stand to simulate ammunition being heated in the sun.

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold

I kept track of the temperatures of the three ammunition samples with a non-contact laser thermometer.

The rifle was fired at room temperature (70 degrees) with all three sets of ammunition. I fired this test at 200 yards out of a return-to-battery machine rest. The aiming point was a leveled line drawn on a sheet of paper. I fired one group with the scope aimed at the line and then moved the aiming point across the paper from left to right for the subsequent groups.

NOTE that the velocity increased as the temperature of the ammunition did.

The ammunition from the freezer shot at 2451 fps.

Frozen FPS

The room temperature ammunition shot at 2500 fps.

Room Temperature FPS

The heated ammunition shot at 2596 fps.

Sierra Bullets Ammunition Ammo temperature temp test hot cold

The tune window of the particular rifle is fairly wide as is shown by the accuracy of the three pressure/velocity levels and good accuracy was achieved across the board. However, notice the point of impact shift with the third group? There is enough shift at 200 yards to cause a miss if you were shooting a target or animal at longer ranges. While the pressure and velocities changed this load was far enough from maximum that perceived over pressure issues such as flattened primer, ejector marks on the case head, or sticky extraction did not appear. If you load to maximum and then subject your ammunition to this test your results will probably be magnified in comparison.

Sierra Bullets Ammunition Ammo temperature temp test hot cold

This test showed that pressures, velocities, and point-of-impact can be affected by temperatures of your ammunition at the time of firing. It’s really not a bad idea to test in the conditions that you plan on utilizing the ammo/firearm in if at all possible. It wouldn’t be a bad idea to also test to see what condition changes do to your particular gun and ammunition combination so that you can make allowances as needed. Any personal testing along these lines should be done with caution as some powder and cartridge combination could become unsafe with relatively small changes in conditions.

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July 10th, 2018

Make Your Own Length-to-Lands Gauge — Quick & Easy

Here’s a tip we feature every year or so, because it is something that costs nothing, yet can be very useful in the reloading process. With a simple, easy modification to a fired case, you can determine the length to lands in your rifle barrel. As long as you set the tension right, the measurements should be repeatable, and you’ve just saved yourself $32 — the price of a commercial OAL gauge.

case OAL gauge home made

To achieve best accuracy with a rifle, you must control bullet seating depth very precisely, so all bullets end up in the same place relative to the entrance of the lands, every time. There may be multiple cartridge OALs which prove accurate. However, with each, you first need to determine a “zero” point — a reliable, and repeatable OAL where the bullet is “just touching” the lands.

There are tools, such as the Hornady (formerly Stoney Point) OAL Gauge, that will help you find a seating OAL just touching the lands. However, the tool requires that you use a special modified case for each cartridge you shoot. And, while we find that the Hornady OAL Gauge is repeatable, it does take some practice to get in right.

Make Your Own Length-to-Lands Gauge with a Dremel
Here’s an inexpensive alternative to the Hornady OAL tool — a slotted case. Forum member Andris Silins explais how to create a slotted case to measure length to the lands in your rifle:

“Here’s what I did to find length to lands for seating my bullets. I made four cuts into the neck of fire-formed brass. Then I pressed the bullet in lightly and chambered the entire gauge. As the cartridge chambers, the bullet slides back into the case to give you length to lands. It took less than five minutes to get it cut and working. A little light oil in the barrel just past the chamber helps ensure the bullet does not get stuck in the lands. It works great and is very accurate.

How to Adjust Tension — Length and Number of Neck Cuts
I made the cuts using a Dremel with a cut-off wheel. You can adjust tension two ways. First, you can make the cuts longer or shorter. Longer cuts = less tension. If you used only three cuts instead of four you would get more tension. The trick is to be gentle when you open and close the bolt. If you ram the bolt closed you may wedge the bullet into the lands. When you open the bolt it helps to keep a finger or two near by to guide the case out straight because the ejector wants to push it sideways.”

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July 6th, 2018

TECH Tip: Safe Loading Practices for Different Bullet Shapes

USAMU Reloading Bullet Safety

This article, from the USAMU Facebook Page, concerns reloading safety. In the relentless quest for more speed and flatter ballistics, some hand-loaders load way too hot, running charges that exceed safe pressure levels. Hint: If you need a mallet to open your bolt, chances are your load is too hot. Stay within safe margins — your equipment will last longer, and you won’t risk an injury caused by over-pressure. In this article, the USAMU explains that you need to account for bullet shape, diameter, and bearing surface when working up a load. Don’t assume that a load which is safe for one bullet will be safe for another even if both bullets are exactly the same weight.

USAMU Reloading tips Army Marksmanship

Today, we continue our handloading safety theme, focusing on not inadvertently exceeding the boundaries of known, safe data.

Bullet manufacturers’ loading manuals often display three, four, or more similar-weight bullets grouped together with one set of load recipes. The manufacturer has tested these bullets and developed safe data for that group. However, seeing data in this format can tempt loaders — especially new ones — to think that ALL bullets of a given weight and caliber can interchangeably use the same load data. Actually, not so much.

The researchers ensure their data is safe with the bullet yielding the highest pressure. Thus, all others in that group should produce equal or less pressure, and they are safe using this data.

However, bullet designs include many variables such as different bearing surface lengths, hardness, and even slight variations in diameter. In fact, diameters can occasionally range up to 0.001″ by design. Thus, choosing untested bullets of the same weight and caliber, and using them with data not developed for them can yield excess pressures.

This is only one of the countless reasons not to begin at or very near the highest pressure loads during load development. Always begin at the starting load and look for pressure signs as one increases powder charges.

Bullet Bearing Surface and Pressure
Bullet bearing surface length (BSL) is often overlooked when considering maximum safe powder charges and pressures. In Photo 1, note the differences in the bullets’ appearance. All three are 7 mm, and their maximum weight difference is just five grains. Yet, the traditional round nose, flat base design on the left appears to have much more BSL than the sleeker match bullets. All things being equal, based on appearance, the RN/FB bullet seems likely to reach maximum pressure with significantly less powder than the other two designs.

Photo 1: Three Near-Equal-Weight 7mm Bullets with Different Shapes
USAMU Bullet Ogive Comparison Safety Reloading

Due to time constraints, the writer used an approximate, direct measurement approach to assess the bullets’ different BSLs. While fairly repeatable, the results were far from ballistics engineer-grade. Still, they are adequate for this example.

Bullet 1 (L-R), the RN/FB, has a very slight taper and only reaches its full diameter (0.284 inch) very near the cannelure. This taper is often seen on similar bullets; it helps reduce pressures with good accuracy. The calculated BSL of Bullet 1 was ~0.324″. The BSL of Bullet 2, in the center, was ~0.430″, and Bullet 3’s was ~ 0.463″. Obviously, bullets can be visually deceiving as to BSL!

Some might be tempted to use a bullet ogive comparator (or two) to measure bullets’ true BSL for comparison’s sake. Unfortunately, comparators don’t typically measure maximum bullet diameter and this approach can be deluding.

Photo 2: The Perils of Measuring Bearing Surface Length with Comparators
USAMU Bullet Ogive Comparision Safety Reloading

In Photo 2, two 7mm comparators have been installed on a dial caliper in an attempt to measure BSL. Using this approach, the BSLs differed sharply from the original [measurements]. The comparator-measured Bullet 1 BSL was 0.694” vs. 0.324” (original), Bullet 2 was 0.601” (comparator) vs. 0.430” (original), and Bullet 3 (shown in Photo 2) was 0.602” (comparator) vs. 0.463” (original). [Editor’s comment — Note the very large difference for Bullet 1, masking the fact that the true full diameter on this bullet starts very far back. You can use comparators on calipers, but be aware that this method may give you deceptive reading — we’ve seen variances just by reversing the comparators on the calipers, because the comparators, typically, are not perfectly round, nor are they machined to precision tolerances.]

Thanks to the U.S. Army Marksmanship Unit for allowing the reprint of this article.

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