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May 1st, 2020

Reloading at the Range — Smart Option for Load Development

Glen Zediker Reloading at Range

Glen Zediker Reloading at RangeThe February 2013 edition of Shooting Sports USA magazine has an interesting feature by Glen Zediker. In this Transporting Success, Part I article, Zediker explains the advantages of loading at the range when your are developing new loads or tuning existing loads. Glen, the author of the popular Handloading for Competition book, discusses the gear you’ll need to bring and he explains his load development procedure. In discussing reloading at the range, Glen focuses on throwing powder and seating bullets, because he normally brings enough sized-and-primed brass to the range with him, so he doesn’t need to de-prime, re-size, and then re-prime his cases.

Zediker writes: “Testing at the range provides the opportunity to be thorough and flexible. You also have the opportunity to do more testing under more similar conditions and, therefore, get results that are more telling. Once you are there, you can stay there until you get the results you want. No more waiting until next time.”

Zediker starts with three-shot groups: “I usually load and fire three samples [with] a new combination. I’ll then increase propellant charge… based on the results of those three rounds, and try three more. I know that three rounds is hardly a test, but if it looks bad on that few, it’s not going to get any better.”

Glen reminds readers to record their data: “Probably the most important piece of equipment is your notebook! No kidding. Write it down. Write it all down.

RCBS Partner PressThere’s More to the Story…

Editor’s Note: In Zediker’s discussion of loading at the range, he only talks about throwing powder and seating bullets. In fact, Glen opines that: “there is little or no need for sizing.” Well, maybe. Presumably, for each subsequent load series, Zediker uses fresh brass that he has previously sized and primed. Thus he doesn’t need to de-prime or resize anything.

That’s one way to develop loads, but it may be more efficient to de-prime, re-size, and load the same cases. That way you don’t need to bring 50, 80, or even 100 primed-and-sized cases to the range. If you plan to reload your fired cases, you’ll need a system for de-priming (and re-priming) the brass, and either neck-sizing or full-length sizing (as you prefer). An arbor press can handle neck-sizing. But if you plan to do full-length sizing, you’ll need to bring a press that can handle case-sizing chores. Such a press need not be large or heavy. Many benchresters use the small but sturdy RCBS Partner Press, on sale now at Amazon for $77.99. You may even get by with the more basic Lee Precision Compact Reloading Press, shown in Zediker’s article. This little Lee press, Lee product #90045, retails for under $35.00.

Glen Zediker Reloading at Range

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April 14th, 2020

Why Cases Can Stick in Dies — And How to Cure the Problem

This article originally appeared in the Sinclair International Reloading Press.

We have all been there…..you place a piece of tumbled brass in the shell-holder of your press, raise it into the die, and suddenly it is like somebody hit the brakes. The case is stuck in the die. Your first instinct is to reverse it out. You crank on the handle, and BANG! The rim rips off the case head and you are looking at a piece of brass stuck in the die.

A stuck case is one of the boo-boos that all of us reloaders have faced from time to time. If proper lubrication is applied, then it should not be a problem. No matter if you are a seasoned reloader or new to it, this situation can happen. Take your time, use the proper procedures, and you will be back in business in no time! This article explains how to avoid stuck cases (through proper lubrication) and how to use a stuck case removal system.

What Causes Stuck Cases
One of the first common mistakes reloaders face is the stuck case. It can be caused by too much or too little lube. Too much and a vacuum can be formed causing the case to become suctioned into the die. Too little lube and friction is the culprit. So what is the cure? There is no exact cure, but the best lube that we have found so far is just a dab of Imperial Sizing Die Wax on your fingers and applied in a thin coat on the body of the case, not the shoulder or neck. Too much of this wax can cause the vacuum effect, or can eventually load your die up with gobs of residue. If it is applied to the shoulder area, or the leftover wax moves up into the shoulder region of the die, you will see dents or dimples in the shoulder. [AccurateShooter.com Editor’s Note: For normal full-length sizing of small cases such as 220 Russian/PPC, 6mmBR, 6.5 Grendel, or 6.5×47 Lapua we recommend Ballistol (aerosol) lube. It is very slippery, goes on very thin, and does not gum up the die.]

A great way to ensure that your dies are clean is to use a simple chamber mop with a dab of your favorite solvent on it and clean out the die. Be sure all of the solvent is out after cleaning by spraying the die out with Quickscrub III or use a clean chamber mop. If you are storing your dies, you can apply a thin coat of a good oil to protect the steel such as TM oil or Starrett M1 Spray.

Using a Stuck Case Removal Kit
If you do stick a case in your die there are a few good stuck case removal kits available. Each one works in a similar fashion. I have found the Hornady kit very effective and easy to use.

Basically what you do is remove the die from the press. Unscrew the decapping assembly and pull it out as far as you can. You then need to drill/tap threads into the stuck case head (this is why it is suggested to unscrew the decapping assembly as far as you can to get it clear of the drill bits). Once this is done screw the die back into the press. You then install the included shellholder attachment on the shellholder ram, and thread it into the case via a small wrench. With some elbow grease you can reverse the stuck case out of the die with the leverage of the press, and not damage the die.

However if the case is stuck….REALLY stuck, you may pull out the threads on the case and you are still left with a stuck case in the die without any way to pull it out. If the case is really difficult to remove even with the use of a stuck case removal kit, do not try to be Hercules with the press ram. Here is a trick that may work. Take the die with the stuck case and place it in your freezer for a couple of hours. Then repeat the removal with the cold die. The freezing temperatures may cause the brass to contract, and make removal easier. If this does not work it is recommended to send it to the die manufacturer. They will be able to remove the case without damaging the die.

Another fix if you can remove the decapping assembly completely is to use a tap hammer and a punch or small wooden dowel to knock the stuck case out. This isn’t the best way since it is very possible that you will damage the die internally or externally on the threads, or both. Send the die to the manufacturer to have this done properly. You will be happier in the long run.

This article appears courtesy Sinclair International. It first appeared in Sinclair’s Reloading Press Blog.

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March 18th, 2020

Can’t Find Varget or Reloder 15? Then Try IMR 4320

IMR 4320 Varget Powder Hodgdon reloading 6mm Dasher

IMR 4320 Varget Powder Hodgdon reloadingWhile Varget and Reloder 15 remain in short supply, you can often find IMR 4320 powder back in the shelves of local gun stores. IMR describes IMR 4320 as follows: “Short granulation, easy metering, and perfect for the 223 Remington, 22-250 Remington, 250 Savage and other medium burn rate cartridges.” This older-generation powder is considerably more temp sensitive than the Hodgdon Extreme propellants, but in the right application, it looks to be a viable alternative for folks who can’t source Varget, Reloder 15, and even H4895.

IMR 4320 Shoots Well in the .308 Winchester
A while back, GS Arizona wrote an excellent Riflemans Journal article, IMR 4320 — the Forgotten Powder. GS developed IMR 4320 loads for his .308 Win Palma rifle and competed with IMR 4320-powered ammo at long range matches. He concluded that: “[IMR 4320] appears to be a very useful alternative to some of the harder-to-get powders. The load is working extremely well at 1000 yards. In the [2009] Arizona Palma State Championship, several high-placing competitors were using the 4320 load. We got sub X-Ring elevation at 1000 yards from several rifles, and that’s all I’m looking for in a Palma load.”

IMR 4320 Works for Dasher Shooter
Forum member FalconPilot shoots a 6mm Dasher with Berger 105gr Hybrids. Looking for an alternative to Varget, he decided to give IMR 4320 a try. The results were good. FalconPilot reports: “I’ve been looking for other options (besides Reloder 15, which I love, but it’s really dirty). While at a gun shop in Ohio, I ran across 8 pounds of IMR 4320. I had never even heard of it, much less tried it. Getting ready for upcoming mid-range shoots, I loaded five rounds with IMR 4320 to the exact same specs as my winning Varget loads for the 6mm Dasher. This recipe was 32.7 grains of powder, Wolf SMR primer, Berger Hybrid 105 jumped fifty thousandths.” Falcon pilot tested his IMR 4320 load at 600 yards:

As you can see from the photo at the top of this article, FalconPilot had good results — a 1.5″ group at 600 yards. He reports: “This group was shoot during the middle of the day, mirage bad, scope set to 25X. It looks like IMR 4320 is a [very close] replacement for Varget… with a tad bit slower burn rate.” FalconPilot tell us the accuracy with IMR 4320 rivals the best he has gotten with Varget: “This gun has always shot under 2 inches [for 5 shots] at 600 yards, and most of time shoots 1.5 to 1.7 inches.”

For comparison purposes, here are Heat of Explosion and Burn Rate values from QuickLOAD for IMR 4320, and for the popular Reloder 15 and Varget powders. You can see that these powders have similar characteristics “by the numbers”:

Manufacturer Powder Brand Heat of Explosion Burning Rate Factor
IMR 4320 3890 0.5920
Alliant Reloder 15 3990 0.5200
Hodgdon (ADI) Varget 4050 0.6150

WARNING — When changing from one powder to another, always start with manufacturer’s stated load data. Start low and work up incrementally. Never assume that loads will be equivalent from one powder to another, even powders with similar burn rates.

What Other Forum Members Say:

I was using IMR 4320 in the mid 70s in my .222 Rem. Darned great powder and I never had a load that was not accurate from the .222 to .30-06 with that powder. — 5Spd

A fine powder overshadowed by the nouveau wave of “gotta have the newest — make me a better shot” powders. Try 4320 in a 22-250 — what a well-kept secret! IMR 4320 meters very well and is a flexible alternative to many of the hard-to-find powders so much in demand. — AreaOne

IMR 4320 was my “go to” powder in my .223 for many many years. This powder and Winchester 55gr soft point bulk bullets (the cheapest bullet I could buy at the time) accounted for thousands of prairie dogs, coyotes, and anything else that needed shooting. I still use IMR 4320 in some .223 loads and am very happy with it still. — pdog2062

I’ve been using it in a .308 Win for several years. I think it is very sensitive to temperature and always waited till the last minute to load my ammo with a close eye on the weekend forecast at the range. IMR 4320 Works pretty good for 155gr Palma and 168gr Hybrid [bullets] in my .308. — JayC

IMR 8208 XBR is also good — if you can find it
Another good substitute for Varget powder in a .223 Rem or .308 Winchester is IMR 8208 XBR. In our own .308 Win tests, this generated slightly more velocity than Varget, with good ES/SD. However, this very good IMR 8208 XBR powder is out-of-stock at many vendors.

IMR 8208 XBR powder

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February 18th, 2020

RCBS Reloading Videos — How to Load Better Ammo Safely

RCBS reloading equipment instruction video series chargemaster progressive rock chucker press case prep

RCBS makes some of the most rugged and durable reloading products you can buy. The RCBS Rock Chucker press is legendary — for good reason. The Editor uses one that has been in my family over twenty years. I also own an RCBS 2000 progressive press that has loaded many thousands of rounds, and features the excellent APS strip priming system. RCBS is serious about reloading, so this company has created a very complete series of instructional videos showing reloading precedures and equipment. You’ll find over 60 videos on the RCBS Video Resources Page and RCBS YouTube Channel.

We encourage readers to check out the RCBS Videos. They can help you master the basics of handloading — case prep, priming, sizing, and bullet seating. In addition, these videos can help you select the right equipment for your loading bench. Videos show presses, case tumblers, ultrasonic cleaning machines, powered case prep centers, and more.

Here are three of our favorite RCBS Reloading videos, along with links to a dozen more:

Basic Safety Precautions for Reloading

Every novice hand-loader should watch this video. It covers the key safety principles you should follow, such as “Don’t use components of unknown origin”. We would add — always double check the labels on your powder bottles, and if you don’t know 100% what powder is in your powder measure — dump it out. Some of the most serious injuries have occurred when reloaders put pistol powder in rifle cases.

Setting Up the Sizing Die Correctly

This video address the common complaint some novices have when their hand-loadeed cartridges won’t chamber properly. Kent Sakamoto explains how to set up the sizing die properly to size the case body and bump the shoulder.

Choosing a Case Cleaning System

Here Kent Sakamoto looks at the three main types of brass cleaning systems: Vibratory Tumbler, Wet Tumbler (with media), and Ultrasonic Cleaning Machine. Kent reviews the pros and cons of each system.

More RCBS Reloading Videos

Here are twelve more helpful videos from RCBS. These cover both reloading techniques and reloading equipment. There are currently over 60 videos on the RCBS YouTube Channel.

Reloading How-To Videos
Case Trimming, Deburring, Chamfering
Measuring Case Length
Crimping — When and How to Crimp
Primer Pocket Cleaning
Priming with a Hand Tool
How to Use an Ultrasonic Machine

Reloading Equipment Videos
Rock Chucker Supreme Kit
RCBS ChargeMaster Lite
RCBS Pro 2000 Progressive Press
Universal Case Prep Center
Summit Single-Stage Press
RCBS Turret Press

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February 7th, 2020

What You Need to Know About Primers — Explained by an Expert

Primer Priming Tool Magnum primers foil anvil primer construction reloading powder CCI
Winchester Pistol Primers on bench. Photo courtesy UltimateReloader.com.

There is an excellent article about primers on the Shooting Times website. We strongly recommend you read Mysteries And Misconceptions Of The All-Important Primer, written by Allan Jones. Mr. Jones is a bona fide expert — he served as the manager of technical publications for CCI Ammunition and Speer Bullets and Jones authored three editions of the Speer Reloading Manual.

» READ Full Primer “Mysteries and Misconceptions” Article

This authoritative Shooting Times article explains the fine points of primer design and construction. Jones also reveals some little-known facts about primers and he corrects common misconceptions. Here are some highlights from the article:

Primer Priming Tool Magnum primers foil anvil primer construction reloading powder CCISize Matters
Useful Trivia — even though Small Rifle and Small Pistol primer pockets share the same depth specification, Large Rifle and Large Pistol primers do not. The standard pocket for a Large Pistol primer is somewhat shallower than its Large Rifle counterpart, specifically, 0.008 to 0.009 inch less.

Magnum Primers
There are two ways to make a Magnum primer — either use more of the standard chemical mix to provide a longer-burning flame or change the mix to one with more aggressive burn characteristics. Prior to 1989, CCI used the first option in Magnum Rifle primers. After that, we switched to a mix optimized for spherical propellants that produced a 24% increase in flame temperature and a 16% boost in gas volume.

Foiled Again
Most component primers have a little disk of paper between the anvil and the priming mix. It is called “foil paper” not because it’s made of foil but because it replaces the true metal foil used to seal early percussion caps. The reason this little disk exists is strictly a manufacturing convenience. Wet primer pellets are smaller than the inside diameter of the cup when inserted and must be compacted to achieve their proper diameter and height. Without the foil paper, the wet mix would stick to the compaction pins and jam up the assembly process.

Read Full Primer Story on ShootingTimes.com

VIDEOS about PRIMERS
Here are two videos that offer some good, basic information on primers:

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February 5th, 2020

Wildcatter’s Road Map — Cartridge Conversion Book

handloaders guide cartridge conversion wildcat obsolete cartridges

Are you a confirmed wildcatter? Do you like to experiment with custom cartridge types? Or do you just like the extra performance you can get from a specialty cartridge such as a 20 Vartarg or 22-250 AI? Well, if you love wildcat cartridges, you’ll probably enjoy this book. Now available for the first time since 2003, The Handloader’s Manual of Cartridge Conversions explains the processes and tools needed to convert standardized brass into hundreds of different rifle and pistol cartridge types. A vast variety of case designs are covered — from vintage cartridge types to modern, cutting-edge wildcats.

handloaders guide cartridge conversion wildcat obsolete cartridges

This classic reference guide has been revised with an easy-to-search format, complete with a full index of hundreds of cartridges. This book belongs on the shelf of any hand-loader who enjoys making and shooting wildcat cartridges. However do note that much of the text is unchanged from earlier editions. For some cartridge types, the author recommends “parent” brass brands that are no longer available. In other situations, there may be more convenient conversions now offered. Nonetheless this is an important resource. As one verified purchaser explains: “Great reference for making the cartridges that are hard to get or no longer in production. Offers an alternative to the the time, expense and effort of having to re-chamber a classic. Saves ‘Grandpa’s shooters’ from becoming safe queens.”

wildcat cartridge case forming Killer Bee Hydraulic
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January 12th, 2020

TECH Tip: Reduce Electronic Scale Drift with Static Guard Spray

Digital Scale Static Guard Static Electricity

Digital Scale Static Guard Static ElectricityApparently reducing static charges on and around electronic scales can reduce their propensity to drift, lessening the problem of “wandering zero”. Just how and why static charges interfere with scale performance is unclear, but many shooters have noticed that static electricity can cause electronic scales to behave strangely. So how do you reduce static charges around your digital balance? GS Arizona, creator of the Rifleman’s Journal Blog, has found a very simple solution — an anti-static aerosol spray — that, by all indications, actually works. When this “spray-can solution” was suggested to GS by a fellow shooter, GS was skeptical. However, he tried the stuff and he says that it really does help the scale maintain zero over time, with much less observed drift.

Static Guard Reduced Scale Drift
GS Arizona explains that the use of “Static Guard” spray helped mitigate the problem of a drifting zero on his Ohaus Navigator electronic scale. He writes: “My electronic scale… suffers from drifting zero (as they all seem to). I’ve read dozens of forum posts about drift and how to minimize its occurrence, so I know this problem isn’t limited to my scale or my workshop. Sometime last year, John Lowther mentioned the use of anti-static spray as a solution to the drift problem. John stated that the spray had virtually eliminated drift for him.”

GS Arizona found that the Static Guard actually worked: “The spray works great, just as John said it would. I spray all surfaces that I touch with my hands and arms as well as the pan (top and bottom), the metal tray on which the pan rests and the table under the scale. In six months or so of using the spray I’ve re-applied it about two or three times; it certainly isn’t something that you need to do each time you sit down to load. Before using the spray, it was not uncommon for me to re-zero the scale 10 times in the course of loading 72 rounds; now it might need it once during a session.”

Permalink Gear Review, Reloading, Tech Tip 6 Comments »
January 2nd, 2020

TEN Worst Reloading Mistakes — Do You Agree with This List?

Shooting Times Reloading Failures Mistakes Top Ten 10

Last fall, Shooting Times released an article entitled “Ten Most Common Reloading Mistakes”. Listed below are the Top Ten mistakes hand-loaders can make, at least according to Shooting Times. What do you think of this list — does it overlook some important items?

Top Ten Reloading Mistakes According to Shooting Times:

1. Cracked Cases — Reloaders need to inspect brass and cull cases with cracks.

2. Dented Cases — Dents or divets can be caused by excess case lube.

3. Excessive Powder Charge — Overcharges (even with the correct powder) can be very dangerous.

4. Primers Not Seated Deep Enough — “High” primers can cause functioning issues.

5. Crushed Primers — Some priming devices can deform primers when seating.

6. Excess Brass Length — Over time, cases stretch. Cases need to be trimmed and sized.

7. Bullets Seated Too Far Out — If the bullet is seated too long you may not even be able to chamber the round. Also, with hunting rounds, bullets should not engage the rifling.

8. Burrs on Case Mouths — Ragged edges on case mouths can actually shave bullet jackets.

9. Excess Crimp — This is a common problem with pistol rounds loaded on progressives. If case lengths are not uniform some cases will get too much crimp, others too little.

10. Inadequate Crimp — This can be an issue with magnum pistol cartridges in revolvers.

Do you agree with this list? We think some important things are missing, such as not adjusting full-length sizing dies properly. This can cause the shoulder to be pushed back too far (or not far enough). Another common mistake is using brass that is worn out, i.e. stretched in the case-head area from multiple cycles of hot loads. We also think the #1 error a reloader can make is using the wrong powder altogether. That can be a fatal mistake. See what happens when you load pistol powder in a rifle.

Permalink Bullets, Brass, Ammo, Reloading 13 Comments »
December 20th, 2019

USAMU Tips for Using a Progressive Reloading Press

Accurateshooter.com USAMU progressive press reloading

Each Wednesday, the U.S. Army Marksmanship Unit (USAMU) publishes a reloading “how-to” article on the USAMU Facebook page. In this article, the USAMU’s reloading gurus help you avoid potentially disastrous mistakes with a progressive — such as double powder changes. The USAMU experts caution that: “beginners would be better served by starting on a single-stage press”. That said, owning a progressive makes sense if you shoot more than 100 centerfire rounds a week. If you own a progressive press, or are thinking of buying one, you should read this article.

USAMU Reloading

For those interested in progressives, we’ll examine different key features among the types and relate them to handloading processes. The first, and simplest, type is the manually-advanced progressive. The shellplate holds the several cartridges being processed with each stroke of the handle. On these presses, the loader must manually advance the shellplate after each handle stroke.

While this obviously slows production vs. a press that cycles the shellplate automatically, this feature does have advantages though. (The disadvantages follow shortly.) No case is advanced to the next station until the operator deliberately does so – which is especially helpful for the new handloader.

Problems that arise during loading can be diagnosed and fixed without fears of some “extra” operation happening unnoticed with cartridges at the other stations. Beginners NOTE: one way to positively prevent this risk is to remove the cases from each press station when a problem emerges, before beginning diagnosis. Usually, however, experienced loaders omit this step as a time-saving measure, being confident in their understanding of the loading machine, process and the appropriate remedy.

Progressive press reloading ultimate reloader USAMU

If all cartridge cases are left in place, the operator must monitor what’s happening at each station. For example, raising the press ram twice may result in a double-charge of powder. With rifle cartridges, this usually results in a massive powder over-flow, alerting the loader to the problem. With pistol cases or small rifle charges in large cases, such an over-flow isn’t guaranteed. [Editor — one way to be sure you don’t have an overcharge or undercharge is to use a Lock-Out Die — see below.] The manually-advanced progressive keeps all operations under the loader’s control at all times. This is intuitively easier for the beginning loader to understand and to operate with confidence.

However, this same characteristic can be problematic if the loader isn’t paying 100% attention to what they are doing during routine operation. Some new handloaders apparently aspire to load progressively while daydreaming and paying little attention to the operation. Their plan is to feed components in, like feeding potato chips to a monkey, while good ammo drops out at the other end. Unfortunately, such an approach may likely result in something other than “good” ammo dropping out at the end…

Forgetting to cycle the shellplate when appropriate will cause problems. As with all handloading, distractions MUST be kept to a minimum for safety purposes. Never watch TV, talk with friends, or have other distractions (such as a rambunctious pet or child) in the room when loading. Avoiding distractions will do much to ensure that one produces consistent, high-quality ammunition, free of defects. For example, when a case doesn’t line up correctly with the case mouth expander or powder drop tube, a difference in “feel” often alerts the loader to correct the problem without ruining a case. If one is interrupted or becomes distracted, be certain to examine ALL cases in the shellplate before resuming loading.

Better Safe Than Sorry — the RCBS Lock-Out Die
RCBS Makes a “Lock-Out Die” that senses the powder charge. This will halt the Progressive press if you have a double charge, or an undercharge. Your Editor has the Lock-Out Die on his RCBS Pro 2000. It has “saved his bacon” a half-dozen times over the years. It can be used on Dillon and Hornady progressives as well as RCBS machines.

Other advantages of the typical manually-advanced progressives are that they are usually simpler in design, with fewer moving parts to get out of adjustment. This appeals to the mechanically dis-inclined! Caliber conversion kits are usually cheaper and take less time to install. This especially benefits the enthusiast who reloads for a wide variety of calibers.

However, many popular manually-advanced progressives have fewer die stations than the higher-end, auto-advancing machines. One item that is very useful when actually dispensing powder on a progressive press is a cartridge case powder-level sensor. This warns if powder levels in each case are too high or too low; however, it does require a die station of its own.

This condition (incorrect powder charges) often results from powder (especially extruded rifle powder) “bridging” in the powder measure. That is, one charge doesn’t fully empty into its cartridge case. This leaves some extra powder hanging up in the measure to join the normal charge in the next case. With some extruded powders, this can be quite obvious without a sensor. However, the sensor can detect small variations that would not be obvious to even an experienced, attentive operator. Considering the machine’s potential to use a powder sensor in addition to one’s other customary dies is a wise idea.

Similarly, pistol shooters are best served to seat bullets and crimp cartridges in separate operations. This should be taken into account when selecting a progressive press. Whenever loading fully-progressively, choosing powders that dispense very easily, e.g., ball/spherical or very fine-grain extruded powders, can help keep charges quite uniform.

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December 10th, 2019

How Changes in Cartridge OAL Can Alter Pressure and Velocity

Berger Bullets COAL length cartridge

Figure 1. When the bullet is seated farther out of the case, there is more volume available for powder. This enables the cartridge to generate higher muzzle velocity with the same pressure.

Berger Bullets COAL length cartridgeEffects Of Cartridge Over All Length (COAL) And Cartridge Base To Ogive (CBTO) – Part 1
by Bryan Litz for Berger Bullets.
Many shooters are not aware of the dramatic effects that bullet seating depth can have on the pressure and velocity generated by a rifle cartridge. Cartridge Overall Length (COAL) is also a variable that can be used to fine-tune accuracy. It’s also an important consideration for rifles that need to feed rounds through a magazine. In this article, we’ll explore the various effects of COAL, and what choices a shooter can make to maximize the effectiveness of their hand loads.

Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI)
Most loading manuals (including the Berger Manual), present loading data according to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) standards. SAAMI provides max pressure, COAL and many other specifications for commercial cartridges so that rifle makers, ammo makers, and hand loaders can standardize their products so they all work together. As we’ll see later in this article, these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge.

Bullet seating depth is an important variable in the accuracy equation. In many cases, the SAAMI-specified COAL is shorter than what a hand loader wants to load their rounds to for accuracy purposes. In the case where a hand loader seats the bullets longer than SAAMI specified COAL, there are some internal ballistic effects that take place which are important to understand.

Effects of Seating Depth / COAL on Pressure and Velocity
The primary effect of loading a cartridge long is that it leaves more internal volume inside the cartridge. This extra internal volume has a well known effect; for a given powder charge, there will be less pressure and less velocity produced because of the extra empty space. Another way to look at this is you have to use more powder to achieve the same pressure and velocity when the bullet is seated out long. In fact, the extra powder you can add to a cartridge with the bullet seated long will allow you to achieve greater velocity at the same pressure than a cartridge with a bullet seated short.

When you think about it, it makes good sense. After all, when you seat the bullet out longer and leave more internal case volume for powder, you’re effectively making the cartridge into a bigger cartridge by increasing the size of the combustion chamber. Figure 1 illustrates the extra volume that’s available for powder when the bullet is seated out long.

Before concluding that it’s a good idea to start seating your bullets longer than SAAMI spec length, there are a few things to consider.

Geometry of a Chamber Throat
The chamber in a rifle will have a certain throat length which will dictate how long a bullet can be loaded. The throat is the forward portion of the chamber that has no rifling. The portion of the bullet’s bearing surface that projects out of the case occupies the throat (see Figure 2).

Berger Bullets COAL length cartridge

The length of the throat determines how much of the bullet can stick out of the case. When a cartridge is chambered and the bullet encounters the beginning of the rifling, known as the lands, it’s met with hard resistance. This COAL marks the maximum length that a bullet can be seated. When a bullet is seated out to contact the lands, its initial forward motion during ignition is immediately resisted by an engraving force.

Seating a bullet against the lands causes pressures to be elevated noticeably higher than if the bullet were seated just a few thousandths of an inch off the lands.

A very common practice in precision reloading is to establish the COAL for a bullet that’s seated to touch the lands. This is a reference length that the hand loader works from when searching for the optimal seating depth for precision. Many times, the best seating depth is with the bullet touching or very near the lands. However, in some rifles, the best seating depth might be 0.100″ or more off the lands. This is simply a variable the hand loader uses to tune the precision of a rifle.

CLICK HERE to Read Full Article with More Info

Article sourced by EdLongrange. We welcome tips from readers.
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