April 20th, 2021

LabRadar Owners — You Should Get this $35 Inertial Trigger

LabRadar chronograph to register bullet speed JKL inertial trigger recoil activated

SUMMARY: This article reviews a device that “triggers” the LabRadar chronograph to register bullet speed. Rather than activate by sound or Doppler reading, this $35 JKL Inertial Trigger works from the rifle’s instantaneous recoil pulse when a shot is fired. After some frustration with his LabRadar when shooting at a range with reflective surfaces, our tester is now reporting that 100% of his actual shots are being captured correctly by his LabRadar chrono equipped with the JKL Inertial Trigger. He won’t use his LabRadar without it now. Other users have become instant fans of this inertial LabRadar trigger as well. It is very affordable and it works great. VIEW LARGE PHOTO.

JKL Inertial Trigger for LabRadar Chronograph

Product Review by F Class John
The LabRadar chronograph has been one of the most revolutionary tools in the shooting world because of how it collects velocity data, how it reports (and stores) that data, and, ultimately, the ease with which it can be positioned and operated. However, it’s not a perfect system. A majority of the complaints come from users whose LabRadar’s sometimes fail to record all the shots fired in a string. For the average plinker, this may not be an issue. But for serious shooters trying to do ladder tests or load development requiring all shots to be reported, it can be frustrating when a shot is missed.

LabRadar chronograph to register bullet speed JKL inertial trigger recoil activated

Traditionally, LabRadar has recommended trying different settings that compensate for the gap between the unit and muzzle as well as well as having different options for how the unit recognizes a shot fired. While these options work to some degree, they aren’t a guaranteed fix especially when shooting at ranges with concrete baffles or with roofs, walls, and dividers that can alter sound waves. While nobody can precisely explain why shots are lost under certain circumstances, the fact remains it DOES happen. In addition, the default system can sometimes pick up stray shots from nearby rifles.

Not willing to give up on this sophisticated chronograph, many shooters have looked for a foolproof way to prevent such failures from happening. In fact, for this shooter, the frustration was so high that I actually sold my first LabRadar and went back to another chronograph before ultimately buying another LabRadar almost a year later. But I made that repeat purchase only after vowing to finding a way to make the LabRadar work — EVERY time, for EVERY shot.

See How JKL Inertial Trigger Works in this Video

JKL Inertial Trigger — Outstanding Product That Works Great
Enter the JKL Trigger for the LabRadar. This is an easy-to-use, inertial-driven trigger that activates simply from the recoil of your gun. The unit consists of a small rectangular pad attached to a long audio cable. All you do is plug in the audio cable, attach the pad to your gun with the provided hook and loop (Velcro) material. Then (important), you must change the LabRadar trigger settings from “Doppler” to “Trigger”. The unit works great and is easy to set up. In my experience, the unit will activate no matter where you place it on a stock. However the recoil of every gun is slightly different, so you will need to make sure you find a location that doesn’t interfere with your shooting setup.

LabRadar chronograph to register bullet speed JKL inertial trigger recoil activated

An unexpected benefit of using the JKL trigger is that it gives you a larger area in which to place your Labradar unit, making it more convenient to setup on benches or range stations. I found this a welcome relief since the LabRadar originally seemed somewhat fussy about where I placed it. Now I can place the LabRadar in more convenient locations — as long as it’s still near my gun and pointed at the target correctly, I get consistent bullet speed data.

LabRadar chronograph to register bullet speed JKL inertial trigger recoil activated

Are There Issues with “False Positives”?
If there is any downside to using the JKL Inertial Trigger, it’s that a very hard bump or aggressive working of the action can trigger a false reading. However these are easy to identify in your data, because the speed value is way lower than true fired shot values. Simply remove that low entry or otherwise ignore it in your calculations. To be fair, this “bump activation” really doesn’t happen very often once you get used to using the inertial trigger.

SUMMARY — Outstanding Accessory for LabRadar Users
Bottom line — if you own a LabRadar, then definitely get a JKL Inertial Trigger. Priced at just $35.00 this device is not expensive, yet it’s one of the most effective accessories you can buy for the LabRadar. I’ve recommended these inertial triggers to dozens of shooters. Every one of those guys who did buy a JKL trigger says they can’t imagine using a LabRadar without one. If you love what the LabRadar can do, but have been frustrated with shots not getting recorded 100% of the time, then definitely get yourself a JKL Inertial Trigger. It turns a good system into an amazing system. JKL Industries states that its inertial trigger “will work on anything from a .22 LR to a suppressed system or with standard rifle and brake.”

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April 19th, 2021

.223 Rem Velocity Per Inch Revealed by Barrel Cut-Down Test

.223 Rem Cut-Down Test barrel UMC m855

Most of us own a .223 Rem rifle. Now, thanks to our friends at Rifleshooter.com we can assess exactly how velocity changes with barrel length for this popular cartridge.

Rifleshooter.com performed an interesting test, cutting the barrel of a .223 Rem rifle from 26″ all the way down to 16.5″. The cuts were made in one-inch intervals with a rotary saw. At each cut length, velocity was measured with a Magnetospeed chronograph. To make the test even more interesting, four different types of .223 Rem/5.56 ammo were chron’d at each barrel length. The Rifleshooter.com team that conducts these tests has a full-service gun shop, 782 Custom Gunworks — visit 782guns.com.

READ RifleShooter.com 5.56/.223 Barrel Cut-Down Test Article »

Test Barrel Lost 25.34 FPS Per Inch (.223 Rem Chambering)
How much velocity do you think was lost, on average, for each 1″ reduction in barrel length? The answer may surprise you. The average speed loss of the four types of .223/5.56 ammo, with a 9.5″ shortening of barrel length, was 240.75 fps total (from start to finish). That works out to an average loss of 25.34 fps per inch.

5.56/.223 Barrel Cut-Down Speed Test 26″ to 16.5″ Start FPS at 26″ End FPS at 16.5″ Total Loss Average Loss Per Inch
UMC .223 55gr 3182* 2968 214 22.5 FPS
Federal M193 55gr 3431 3187 244 25.7 FPS
Win m855 62gr 3280 2992 288 30.3 FPS
Blk Hills .223 68gr 2849 2632 217 22.8 FPS

*There may have been an error. The 25″ velocity was higher at 3221 fps.

See inch-by-inch Barrel Cut-Down Velocity Data HERE »

Rifleshooter.com observed: “Cutting the barrel from 26″ to 16.5″ resulted in a velocity reduction of 214 ft/sec with the UMC 223 55-grain cartridge, 244 ft/sec with the Federal M-193 cartridge, 288 ft/sec with the Winchester M855 cartridge and 217 ft/sec with the Back Hills 223 68-grain match cartridge.”

How the Test Was Done
The testers described their procedure as follows: “Ballistic data was gathered using a Magnetospeed barrel-mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation were logged for each round. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length. Temperature was 45.7° F.”

CLICK HERE to Read the Rifleshooter.com Test. This includes detailed charts with inch-by-inch velocity numbers.

See More Barrel Cut-Down Tests on Rifleshooter.com
Rifleshooter.com has performed barrel cut-down tests for many other calibers/chamberings including 6mm Creedmoor, .308 Winchester, and .338 Lapua Magnum. See these test results at Rifleshooter.com.

.308 Win barrel length cut test

Much Different Results with 6mmBR and a Longer Barrel
The results from Rifleshooter.com’s .223/5.56 test are quite different than the results we recorded some years ago with a barrel chambered for the 6mmBR cartridge. When we cut our 6mmBR barrel down from 33″ to 28″ we only lost about 8 FPS per inch. Obviously this is a different cartridge type, but also our 6mmBR barrel end length was longer than Rifleshooter.com’s .223 Rem start length. Velocity loss may be more extreme with shorter barrel lengths. And, of course, different cartridge types and powder/bullet combinations will yield different results.

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April 18th, 2021

Sunday Gunday: 20 Practical 4200+ FPS Varmint Slayer

.20 20 practical varmint cartridge .204 Tikka lilja Warren

Do you have .20-Cal fever? Do you yearn to see what a 4200+ fps projectile can do to an unsuspecting prairie dog? Well you could go out and purchase a 204 Ruger rifle, fork over the money for a new, complete die set, and hope that the brass is in stock. Warren B (aka “Fireball”) has a more cost-effective solution. If you have .223 Rem dies and brass, all you need to shoot the 20 Practical is a new barrel and a .230″ bushing to neck down your .223 cases. Warren’s wildcat is simple, easy, and economical. And the 20 Practical matches the performance of the highly-publicized 20 Tactical with less money invested and no need to buy forming dies or fire-form cases. Warren’s cartridge was aptly named. Practical it is.

20 Practical Tikka Bolt Action for Varminting

by Warren B (aka “Fireball”) and Kevin Weaver

After building my 20 PPC, I wanted to do another .20 caliber, this time a repeater for predator hunting that could also serve as a gopher/prairie dog rifle. I wanted to use a Tikka M595 stainless sporter I had. This rifle is the ultimate repeater with an extremely smooth-feeding cycle from its single-column magazine. Since the Tikka was a .223 Remington from the factory, I first looked at possible case designs that would fit the magazine. The 204 Ruger was a very new round at the time and brass was scarce. I also didn’t care for the overly long case design or the standard throat dimensions of the cartridge. I then looked at the 20 Tactical. It was a nice cartridge but I didn’t like the fact that (at the time) an ordinary two-die Tac 20 set with just a plain full-length die and standard seater were $150. Not only did the costs bother me, but I was accustomed to using a Redding die set featuring a body die, a Type-S bushing neck die, and a Competition seater. To be honest, I also didn’t care for the 20 Tactical’s name–there is absolutely nothing tactical about the cartridge. I didn’t want to adopt a new cartridge based on what I perceived to be a marketing gimmick (that “tactical” title).


Warren B, aka “Fireball”, with his Tikka 595. With its smooth action and phenolic single-column mag, it cycles perfectly in rapid fire.

.20 20 practical varmint cartridge .204 Tikka lilja WarrenSimply Neck Down .223 Rem to Make a 20-223 Wildcat
I decided the best thing to do for my purposes was to simply neck down the .223 Rem case and make a 20-223. I already had the dies, the brass, and a rifle that would feed it perfectly. I decided to call the cartridge the 20 Practical because as you will see in this article, it truly is a very practical cartridge. In addition to the generous and inexpensive availability of brass and dies, the 20 Practical is an easy case to create, requiring no fire forming as a final step. Simply neck your .223 Rem cases down, load and shoot.

[Editor’s Note: Over the years, other shooters have experimented with .223 Remington cases necked down to .20 caliber, some with longer necks, some with different shoulder angles. Warren doesn’t claim to be the first fellow to fit a .20-caliber bullet in the .223 case. He gives credit to others who did pioneering work years ago. But he has come up with a modern 20-223 wildcat that involves no special case-forming, and minimal investment in dies and tooling. He commissioned the original PTG 20 Practical reamer design, and he and Kevin did the field testing to demonstrate the performance of this particular version.]

I chose Kevin Weaver at Weaver Rifles to fit and chamber the barrel to my rifle. Kevin does excellent work and is great to work with. Kevin liked the idea of the 20 Practical so much he agreed to purchase the project reamer. (BTW Kevin didn’t even need to purchase a Go/No-Go gauge, he just used an existing .223 Rem gauge.)

Before Kevin ordered the reamer, I talked over the reamer specs with him. My priorities were tolerances on the tight end of the .223 Rem SAAMI specification, a semi-fitted neck with no need for neck-turning, and a short throat so that we could have plenty of the 32gr V-Max in the case and still touch the lands. I also wanted this short throat in case [anyone] wanted to chamber an AR-15 for the 20 Practical. A loaded 20 Practical round will easily touch the lands on an AR-15 while fitting into the magazine with no problem. With its standard 23-degree shoulder, the 20 Practical case also feeds flawlessly through an AR-15.

As for the barrel, I only use Liljas on my rifles. I have had great luck with them. They have always shot well and they clean up the easiest of any barrels that I have tried. I had previously sent my Tikka barreled action to Dan Lilja so that he could program a custom contour into his equipment and turn out a barrel that would perfectly fit the factory M595 sporter stock. There isn’t much material on an M595 sporter stock so the contour had to match perfectly and it did. Dan Lilja now has this custom contour available to anyone who would like to rebarrel their M595 sporter with one of his barrels.

There Are Plenty of Good .204-Caliber Varmint Bullet Options
20 Practical .204 Ruger .20 caliber bullets

How to Form 20 Practical Cases — Simple and Easy
Forming 20 Practical cases is very easy. No fire-forming is required. Start with any quality .223 Rem brass. Then simply run the case into your bushing die with the appropriate bushing and call it done.

Project Componentry
My 20 Practical rifle started out as a Tikka Model 595 Stainless Sporter in .223 Remington. Though the M595 is no longer imported, if you shop around you can find M595 Sporters for bargain prices. Mine cost under $500. I think the action alone is worth that! The receiver has a milled dovetail for scope rings plus a side bolt release like expensive BR actions. The bolt cycles very smoothly. Ammo is handled with super-reliable 3- or 5-round detachable single-column magazines (FYI, Tikka’s M595 22-250 mags will feed a 6BR case flawlessly.) We kept the standard Tikka trigger but fitted it with a light-weight spring. Now the trigger pull is a crisp 1.8 pounds–about as good as it gets in a factory rifle. We replaced the factory tube with a custom, 24″, 3-groove Lilja 12-twist barrel. Dan Lilja created a special M595 sporter contour to allow a perfect “drop-in” fit with the factory stock. For optics, I’ve fitted a Leupold 4.5-14x40mm zoom in low Talley light-weight aluminum mounts. All up, including optics and sling, my 20 Practical weighs just under 8.5 pounds.

Test Report–How’s It Shoot?
I sent the barrel and barreled action to Kevin and in a very short time it was returned. Kevin did a perfect job on the rifle. I had asked him to try to match the bead blasted finish of the Tikka when he finished the new barrel. It came out perfect and the only way one can tell it is a custom is the extra two inches of length and the “20 Practical” cartridge designation.

So, no doubt you’re asking “how does she shoot?” Is my “prototype”, first-ever 20 Practical an accurate rig? In a word, yes. Even with the standard factory stock, and light contour barrel, it can shoot 3/8″ groups. Take a look at the typical target from this rifle. This is from an 8.5-pound sporter with a very skinny fore-end and a factory trigger.

Gunsmith’s Report from Kevin Weaver
The 20 Practical: Origins and Development

Editor’s NOTE: We can’t say for sure who first necked down the .223 Rem to .20 caliber and chambered a rifle for that wildcat (as opposed to the .20 Tactical). But here is an account from way back in 2006 when the Warren B first came up with the idea of a .20 Practical cartridge, complete with reamer specs.

A year ago I received a call from Warren with a great idea. Warren asked “Why couldn’t we simply neck down the .223 Remington case to 20 caliber and get basically the same performance as the 20 Tactical? This way you can forgo the expensive forming dies that are needed for the 20 Tactical.” The idea made perfect sense to me, and I saw no major technical issues, so we got started on the project. I ordered a reamer from Dave Kiff at Pacific Tool & Gauge (PTG) with a .233″ neck. The .233″ neck should allow for a simple necking-down of the 223 Remington case to produce the 20 Practical in just one step. No fire-forming necessary! Furthermore, the PTG 20 Practical reamer Dave created should work with any available .223 Rem brass, commercial or military.

The first 20 Practical round was launched down range (through Warren’s Tikka) just a few months later. The brass formed as easily as expected. All one needs is a Redding type “S” bushing die with a .230 bushing and with just one step I had a .20 caliber case ready to shoot. Warren is brilliant. [Editor’s Note: We concur. For more details on Warren’s case-forming methods and his tips for adapting .223 Rem dies, read the technical sections further down the page.]

It would be almost six months later until I got around to building a dedicated test rifle chambered for the 20 Practical. I used a Remington 722 action, Remington synthetic semi-varmint stock, and a 24″ Douglas stainless steel XX 12-twist barrel. I formed and loaded about 30 cases using Remington brass in about 20 minutes. I used a .223 Rem seating die to seat the 20 Practical bullets. The .223 seating stem seated the small 20-Cal bullets just fine. The first loads sent the 40gr Hornady V-Max bullets down range at a modest 3500 FPS. I did not shoot for groups. I just wanted to use this load to sight in the rifle and break in the barrel. Load development was painless–I used reduced .223 Rem loads for 40gr bullets and worked up from there. In the table below are some of my preferred loads as well as Warren’s favorite recipes for his 20 Practical.

Bullet Wt. Powder Charge Wt. Velocity FPS Comments
32GR H4198 24.1 4025 Warren’s lighter gopher load
32GR AA2460 27.8 4154 Warren’s coyote/prairie dog load
32GR N133 26.0 4183 Coyote/PD load, clean burn
33GR H4198 26.0 4322 Hot Load. Use with Caution!
33GR N133 27.0 4255 Kevin: 0.388” 5 shot group
40GR H335 25.0 3583 Kevin’s barrel break-in load
40GR H4198 24.0 3907 Hodgdon “Extreme” Powder
40GR IMR4895 26.0 3883 Kevin: 0.288″ 5-shot group
40GR N133 25.0 3959 Kevin: 0.227″ 5-shot group
Warren’s Load Notes: My pet loads are all with IMI cases, 32gr Hornady V-Maxs, and Fed 205 primers (not match). These are the most accurate loads in my rifle so far. I haven’t even bothered with the 40s as I have the 20 PPC and 20 BR for those heavier bullets. I prefer the lighter bullets in the 20 Practical because I wanted to keep speed up and recoil down in this sporter-weight predator rifle. Also, the 32gr V-Max is exceptionally accurate and explosive. I like N133 the best as it burns so clean. IMI cases are tough and well-made.
Kevin’s Load Notes: I used Remington 223 cases, Hornady V-Max bullets, and Remington 6 1/2 primers to develop the above loads. CAUTION: all loads, both Warren’s and mine, should be reduced 20% when starting load development in your rifle. All load data should be used with caution. Always start with reduced loads first and make sure they are safe in each of your guns before proceeding to the high test loads listed. Since Weaver Rifles has no control over your choice of components, guns, or actual loadings, neither Weaver Rifles nor the various firearms and components manufacturers assume any responsibility for the use of this data.

Comparing the 20 Practical and 20 Tactical
Kevin tells us: “The 20 Practical and the 20 Tactical are almost identical cartridges. There are only slight differences in case Outside Diameter, shoulder angle, and case body length. The neck length on the 20 Tactical is a bit longer, but there is still plenty of neck on the 20 Practical to grip the popular bullets, such as the 32gr V-Max. Here are some specs:

Cartridge Bolt face to shoulder Shoulder O.D. Shoulder Angle Total length
20 Tactical 1.5232″ .360 30° 1.755″
20 Practical 1.5778″ .3553 23° 1.760″

Both the 20 Tactical and the 20 Practical are fine .20 caliber cartridges. At present, the 20 Tactical is the more popular of the two because it has had more publicity. However, my favorite would be the 20 Practical. Warren’s 20 Practical gives the SAME performance as the 20 Tactical without fire-forming, or having to buy expensive forming dies. So with the 20 Practical you do less work, you shell out a lot less money, yet you give up nothing in performance. What’s not to like? To create 20 Practical cases, just buy a .223 Rem Redding Type “S” Bushing Die set with a .230 or .228 bushing and have fun with this great little cartridge.”

(more…)

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April 18th, 2021

Are You a Gun Wizard? Take the Shoot 101 Ballistics Quiz

Shoot 101 Ballistics Question Quiz BC trajectory

Shoot 101 Quiz
How much of an expert are you when it comes to firearms and ballistics? Test your knowledge with this interactive test. Vista Outdoor, parent of CCI, Federal, Bushnell, RCBS and other brands, has a media campaign called Shoot 101, which provides “how to” information about shooting, optics, and outdoor gear. There were a variety of interactive offerings that let you test your knowledge.

On the Shoot 101 website, you’ll find a Ballistics Quiz. The questions are pretty basic, but it’s still fun to see if you get all the answers correct.

You don’t need a lot of technical knowledge. Roughly a third of the questions are about projectile types and bullet construction. Note, on some platforms the layout doesn’t show all FOUR possible answers. So, for each question, be sure to scroll down to see all FOUR choices. REPEAT: Scroll down to see ALL answers!

CLICK HERE to Go to SHOOT 101 Ballistics QUIZ Page »

Sample Ballistics Question 1:

Shoot 101 Ballistics Question Quiz BC trajectory

Sample Ballistics Question 2:

Shoot 101 Ballistics Question Quiz BC trajectory

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April 17th, 2021

G1 vs. G7 Ballistic Coefficients — What You Need to Know

G1 G7 BC drag models

Over the past 12 months, this article was one of the TOP 20 most-read Daily Bulletin features. We’re reprising it today for those who may have missed it the first time. The above diagram comes from a TiborasurasRex YouTube Video comparing G1 and G7 BC models. CLICK HERE to watch the video.

The better, up-to-date ballistics programs let you select either G1 or G7 Ballistic Coefficient (BC) values when calculating a trajectory. The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. You’ve probably seen that G7 values are numerically lower than G1 values for the same bullet (typically). But that doesn’t mean you should select a G1 value simply because it is higher.

Some readers are not quite sure about the difference between G1 and G7 models. One forum member wrote us: “I went on the JBM Ballistics website to use the web-based Trajectory Calculator and when I got to the part that gives you a choice to choose between G1 and G7 BC, I was stumped. What determines how, or which one to use?”

The simple answer is the G1 value normally works better for shorter flat-based bullets, while the G7 value should work better for longer, boat-tailed bullets.

G1 vs. G7 Ballistic Coefficients — Which Is Right for You?
G1 and G7 refer both refer to aerodynamic drag models based on particular “standard projectile” shapes. The G1 shape looks like a flat-based bullet. The G7 shape is quite different, and better approximates the geometry of a modern long-range bullet. So, when choosing your drag model, G1 is preferable for flat-based bullets, while G7 is ordinarily a “better fit” for longer, boat-tailed bullets.

G1 G7 Ballistic coefficients

Drag Models — G7 is better than G1 for Long-Range Bullets
Many ballistics programs still offer only the default G1 drag model. Bryan Litz, author of Applied Ballistics for Long Range Shooting, believes the G7 standard is preferrable for long-range, low-drag bullets: “Part of the reason there is so much ‘slop’ in advertised BCs is because they’re referenced to the G1 standard which is very speed sensitive. The G7 standard is more appropriate for long range bullets. Here’s the results of my testing on two low-drag, long-range boat-tail bullets, so you can see how the G1 and G7 Ballistic coefficients compare:

G1 BCs, averaged between 1500 fps and 3000 fps:
Berger 180 VLD: 0.659 lb/in²
JLK 180: 0.645 lb/in²

The reason the BC for the JLK is less is mostly because the meplat was significantly larger on the particular lot that I tested (0.075″ vs 0.059″; see attached drawings).

For bullets like these, it’s much better to use the G7 standard. The following BCs are referenced to the G7 standard, and are constant for all speeds.

G7 BCs:
Berger 180 VLD: 0.337 lb/in²
JLK 180: 0.330 lb/in²

Many modern ballistics programs, including the free online JBM Ballistics Program, are able to use BCs referenced to G7 standards. When available, these BCs are more appropriate for long range bullets, according to Bryan.

[Editor’s NOTE: BCs are normally reported simply as an 0.XXX number. The lb/in² tag applies to all BCs, but is commonly left off for simplicity.]

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April 17th, 2021

Primer Blow-Out Danger — Yes Always Wear Eye Protection!

Primer Blown Gas defect winchester casehead

A few years back, Our friend Grant Guess had a “close encounter” with a bad primer. An apparently defective primer caused part of the casehead on one of his rounds to blow out. This, in turn, allowed high pressure gas to vent through the damaged primer pocket. Take a good look, boys and girls. This is yet another very good reason to wear safety glasses … EVERY time you shoot. The cartridge was a 6.5-06, handloaded in necked-down Winchester-headstamp .270 Win brass. Grant reports:

“I had a blow through between the primer and the primer pocket today. The action was really smoking and I got a face full of gas. This was a reasonably light charge. Thank God for safety glasses.

I should also mention that it appears there is a 3/64 hole that is halfway between the primer and the primer pocket. Like it burned a small jet hole through both of them.”

Could this happen to you? It just might. On seeing this damaged case, one of Grant’s Facebook friends, Chris D., observed: “Search the internet, you will see a lot of these pin hole ‘in the corner’ failures. Obviously Winchester has some issues with the LR primers.”

Careful Examination Reveals Apparent Primer Defect
After this incident, Grant examined the damaged case: “I pinned the flash hole and it is not over-sized or under-sized. The primer clearly has an area where it had a defect. At [50,000 CUP], it doesn’t take much of a defect to cause issues. There was a slight bit of pucker-factor on the next shot….”

Primer Blown Gas defect winchester casehead

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April 16th, 2021

How Bullet Bearing Surface Length Can Affect Load Pressure

USAMU Bullet Ogive Comparison Safety Reloading
Three near-equal-weight 7mm bullets with different shapes and bearing surface.

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.

USAMU Bullet Ogive Comparison Safety Reloading

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.

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

USAMU Bullet Ogive Comparison Safety ReloadingBullet 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.

Note: 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.

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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April 16th, 2021

Muzzle Brake Noise Levels Revealed by PRB Field Tests

PrecisionRifleBlog.com Cal Zant Muzzle Brake Test Noise Level Decibels Suppressor

A while back, Cal Zant at PrecisionRifleBlog.com did a big muzzle brake comparison test. Along with measuring recoil reduction, Cal’s team recorded sound levels in PRB’s exhaustive muzzle brake field test. In the PRB archives you’ll find comprehensive muzzle brake sound test results, with hard data on 20 different muzzle brakes.

Sound can be a tricky subject, but Cal Zant, the editor of PrecisionRifleBlog.com, presents everything an informed shooter should know about muzzle brake noise in a straightforward and practical way. Most sound tests are measured from the side of the muzzle, in accordance with mil-spec standards, and Cal did that. But he also measured the sound level of each brake from behind the rifle, closer to the shooter’s position. This provides a more accurate indicator of the actual sound levels firearms operators will encounter while shooting.

Muzzle brakes ARE really loud — that’s something most active shooters have observed. But this study finally gives us some hard data and makes objective comparisons. The difference between brakes was quite significant. Some brakes were ear-splitting — more than twice as loud as other brakes tested.

As a bonus, Cal also provides data on how the new Ultra series suppressors from Thunder Beast Arms Corp (TBAC) compare in terms of sound level behind the rifle.

Check out the Test Results: http://precisionrifleblog.com/2015/08/07/muzzle-brakes-sound-test.

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April 15th, 2021

Go Big or Go Home — Care and Feeding of .50 BMG Rifles

fifty caliber shooting association

Owning and Feeding ‘The Big Bore’ — .50 BMG

Is The Challenge Of Big Bore Extreme Range Shooting Right For You?
By James Patterson
This article originally written for the Sinclair Reloading Press

Fifty 50 Caliber shooting Association

Handling a .50 BMG Rig
Is a .50 BMG caliber rifle difficult to shoot? Not at all. The relatively heavy weight of a standard rifle at 30 pounds or more combined with a very efficient muzzle brake makes it a pleasure to shoot. The typical recoil can be compared to a .243 rifle or a 12 gauge trap load. On the other hand, the burning of a typical load of 230 grains of powder combined with that muzzle brake makes the muzzle blast experience exhilarating. A first time shooter will fire, pause for a moment in awe at the muzzle blast, and then break out into what has become known as “The 50 Caliber Grin”, almost impossible to wipe from ones face. My daughter started competing with the .50 BMG at 18 (115 lbs of tall skinny girl) and happily shoots 100+ rounds in the course of a match, her grin on the last round is as wide as on the first! Many members and competitors in the FCSA are women and many have distinguished themselves as excellent marksman having set world records on numerous occasions.

50 BMG FCSA 50 Caliber 50 BMG

50 BMG Fifty Caliber Shooting Association

Cost of Big-Bore Shooting
Is owning and shooting a .50 BMG caliber rifle expensive? Relatively speaking yes, but one must put it into perspective. Rifles may run from $2500 to $7000, maybe even more for a top of the line custom rifle. A good scope will set you back $1000 to $3500. And while excellent commercial ammo is made, it is hard to find these days and runs from $4 to $6 a round. Most serious shooters start reloading for the rifle as soon as practical, not only for the economics of reloading but also for the ability to fine tune custom ammo for their specific rifle. It’s a very rare match that is won shooting commercial ammo. I recently compared the cost of my hobby — owning, shooting, and competing with the 50 BMG — with a friend whose hobby is snowmobiling. Factoring in the cost of equipment, licensing, gasoline, clothing, etc. it was soon obvious that my hobby was significantly less expensive than his.

50 BMG FCSA Fifty Caliber

50 BMG FCSA fifty Caliber

FCSA 50 Caliber 50 BMG

Getting Started
FCSA 50 BMG Fifty Caliber Shooting AssociationSo how does one get started? You could do as I did, purchase a rifle not knowing what you were really getting into; or you could come out to a FCSA-sponsored event, shoot a number of different rifles, rub shoulders with those who have already taken the plunge, and see if this sport is right for you. While membership in the Fifty Caliber Shooters Association (FSCA) is required to compete at a FSCA event, membership is not required to come and experience first hand what is going on. If you have any inclination that you are interested in the extreme sport of long rang, big bore shooting then a year’s membership in the FCSA is only $60 ($20 for active duty military) a significant bargain if it helps you make just one well-informed equipment choice. In addition one of the primary functions of the FCSA is helping to identify active members near you who can help you understand just what is involved and help you ‘get your feet wet’ in this challenging sport.

FCSA 50 Caliber 50 BMG

Photos courtesy FCSA Photo Gallery.
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April 15th, 2021

Co-Ax, Rock Chucker, Summit — Three Press Comparison Test

RCBS Rockchucker Rock Chucker Forster Co-Ax Coax Summit single-stage Press Hornady Laurie Holland Target Shooter

“The press is the heart of the handloading operation, also traditionally the most expensive single tool employed…” — Laurie Holland

British competitive shooter Laurie Holland has reviewed three popular, single-stage reloading presses for Target Shooter Magazine (targetshooter.co.uk). Laurie bolted up a Forster Co-Ax, RCBS Rock Chucker Supreme, and RCBS Summit to his reloading bench and put the three presses through their paces. These three machines are very different in design and operation. The venerable Rock Chucker is a classic heavy, cast-iron “O”- type press that offers lots of leverage for tough jobs. The smaller RCBS Summit press is an innovative “upside-down” design with a large center column and open front. It offers a small footprint and easy case access from the front. The Co-Ax is unique in many respects — dies slide in and out of the upper section which allows them to “float”. The cartridge case is held in the lower section by spring-loaded jaws rather than a conventional shell-holder.

READ Laurie Holland Reloading Press 3-Way Comparison Review

If you are considering purchasing any one of these three presses, you should read Laurie’s article start to finish. He reviews the pros and cons of each press, after processing three different brands of brass on each machine. He discusses ergonomics, easy of use, press leverage, smoothness, priming function, and (most importantly), the ability to produce straight ammo with low run-out. The review includes interesting data on case-neck run-out (TIR) for RWS, Federal, and Norma 7x57mm brass.

RCBS Rockchucker Rock Chucker Forster Co-Ax Coax Summit single-stage Press Hornady Laurie Holland Target ShooterReview Quick Highlights:

RCBS Rock Chucker Supreme
“My expectations of the antediluvian RCBS Rock Chucker Supreme’s performance weren’t over high to be honest as I mounted it in the place of the Summit. As soon as I sized the first of the stretched RWS cases though, I saw why this press has been such a long-running favorite. The workload was considerably reduced compared to the other two presses and doing 40-odd cases took no time at all with little sweat — it just eats hard-to-size brass.”

RCBS Summit Press
“Despite its massive build and long-stroke operating handle, [the Summit] took more sweat than I’d expected, even if it was somewhat less work than with the Co-Ax. Although the Summit is apparently massive, I noticed that the die platform would tilt fractionally under the heaviest strains[.] It is nevertheless a very pleasant press in use and bullet seating was a doddle — the few examples tried proving very concentric on checking them afterwards. The optional short handle would be valuable for this task.”

Forster Co-Ax
“[On the Co-Ax], the operating handle is above the machine, located centrally here [with] twin steel links at the top end of the press dropping down to the moving parts. The Co-Ax incorporates a number of novel features, principally its automatic and multi-case compatible shell-holder assembly with spring-loaded sliding jaws, very neat spent primer arrangements that allow hardly any gritty residues to escape and foul the moving parts and, the snap-in/out die fitment that allows rapid changes and also sees the die ‘float’ in relation to the case giving very concentric results. I own this press and it meets my handloading needs very well.”

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April 14th, 2021

Home-Built Wood Cleaning Cradles — Great DIY Project

IBS Piedmont 600-yard match

We saw some interesting gear at a 600-yard IBS match at the Piedmont Gun Club (Rutherfordton, NC) a few seasons back. On display were a variety of hand-made wood cleaning cradles designed to fit on table tops. These typically employ a box-style design, with layer of cloth or other padding to cushion the underside of the stock. On display were both single-rifle cleaning cradle/boxes and dual-rifle rigs. This is a good do-it-yourself project that can be built with simple tools.

Click Photos to View Large Versions
IBS Piedmont 600-yard match

Notice that these cradle-boxes feature an extended lower section in the rear. This lower “lip” butts up against the edge of the table so the whole assembly stays in place. In the photo above it appears that the lower section may actually be cut from a rubber block, but we’re not sure.

IBS Piedmont 600-yard match


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April 13th, 2021

Tuesday Trivia: Can You Over-Stabilize a Bullet?

spinning bullet stabilizationOn the Applied Ballistics Facebook page a few seasons ago, Ballistician Bryan Litz posed a “Tuesday Trivia” question about ballistics. This being Tuesday we thought we’d bring back this interesting brain-teaser — a true/false question about bullet stabilization. On shooting forums you often find heated arguments about “over-stabilization”. Bryan wants readers to consider the issue of over-stabilization and answer a challenge question…

Is This Statement TRUE or FALSE?

“The problem with ‘over-stabilizing’ a bullet (by shooting it from an excessively fast twist rate) is that the bullet will fly ‘nose high’ on a long range shot. The nose-high orientation induces extra drag and reduces the effective BC of the bullet.”

True or False, and WHY?

Click the “Post Comment” link below to post your reply (and explain your reasoning).

Bullet Movement in Flight — More Complicated Than You May Think
Bullets do not follow a laser beam-like, perfectly straight line to the target, nor does the nose of the bullet always point exactly at the point of aim. Multiple forces are in effect that may cause the bullet to yaw (rotate side to side around its axis), tilt nose-up (pitch), or precess (like a spinning top) in flight. These effects (in exaggerated form) are shown below:

spinning bullet stabilization

Yaw refers to movement of the nose of the bullet away from the line of flight. Precession is a change in the orientation of the rotational axis of a rotating body. It can be defined as a change in direction of the rotation axis in which the second Euler angle (nutation) is constant. In physics, there are two types of precession: torque-free and torque-induced. Nutation refers to small circular movement at the bullet tip.

Diagram from the University of Utah Health Sciences Library Firearm Ballistics Tutorial
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April 12th, 2021

Insanely Good 3D Animation of Pistol Firing Sequence

GECO Ruag Ammotec RWS ammo 3D animation video

Here’s a very cool 3D Animation showing pistol rounds being fired. Computer-generated graphics provide a look inside the cartridge at the moment of ignition as the primer fires and the flame front moves through the ignited powder. It’s really kind of mesmerizing. If you’ve every wondered just what happens inside your cartridges the moment that firing pin strikes, then watch this video…

Watch Video to See Handgun Ammo Being Chambered and Fired:

Mute Enabled — Click Speaker Icon to Hear Audio. Firing Sequence Starts at 1:28.

GECO Ruag Ammotec RWS ammo 3D animation videoThis animated video from German ammo-maker GECO (part of the Swiss RUAG group of companies) reveals the inside of a pistol cartridge, showing jacket, lead core, case, powder and primer. Employing advanced 3D rendering and computer graphics, the video shows an X-ray view of ammo being loaded in a handgun, feeding from a magazine.

Then it really gets interesting. At 1:28 – 1:50 you’ll see the firing pin strike the primer cup, the primer’s hot jet streaming through the flash-hole, and the powder igniting. Finally you can see the bullet as it moves down the barrel and spins its way to a target. This is a very nicely-produced video. If you’ve ever wondered what happens inside a cartridge when you pull the trigger, this video shows all. They say “a picture’s worth a thousand words”… well a 3D video is even better.

GECO Ruag Ammotec RWS ammo 3D animation video

GECO Ruag Ammotec RWS ammo 3D animation video

GECO Ruag Ammotec RWS ammo 3D animation video

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April 8th, 2021

Get FREE Bushnell Ballistics APP with Applied Ballistics Software

Bushnell Applied Ballistics App iOS Android Google Play

Bushnell offers a good FREE new Ballistics App powered by the Applied Ballistics Ultralite Engine. The new Bushnell Ballistics App easily calculates ballistic solutions for any popular cartridge type once you input velocity, BC, and atmospherics. The App features trusty Applied Ballistics bullet data, and it can even pull in atmospheric data from web weather sources. This allows you to calculate hold-overs and make precise wind corrections. The App is offered in both iOS (Apple) and Android OS versions.

“The Bushnell Ballistics App is powered by the Applied Ballistics Ultralite engine, the most trusted ballistics data-cruncher in the industry,” said Bushnell Marketing Manager Matt Rice. “This App allows users to easily build and modify gun profiles and build range cards to calculate firing solutions based on their specific scope and ammunition choices. All of our Bushnell scopes and reticles have been pre-loaded [in the App].”

Bushnell Applied Ballistics App iOS Android Google Play

The Bushnell App features AB Connect, a live library of G1/G7 data, plus the Applied Ballistics Bullet Library with 740+ pre-loaded bullet profiles. The Bushnell scope library features 150+ scopes and 30 reticle options. Atmospheric data can be updated manually or directly from the internet (when connected). Angle range compensation is also calculated. Gun profile management provides up to five saved profiles with reticle-based firing solutions. A multiple target feature saves up to five targets. Range cards can be shared or printed using the Email Range Card Function.

The FREE App works on both Android and iOS operating systems, and is available on Google Play and the Apple App Store. It is optimized for Bushnell riflescopes and reticles, but is compatible with all optics. Once downloaded, the App functions off the grid — no cell service required.

“The new Bushnell Ballistic App puts the power of long-range, first-shot accuracy into the hands of any shooter,” Rice said. “it was designed to perform in any condition and to offer our consumers true value, with features that far exceed the price — which, in this case, is free!”

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April 6th, 2021

Springfield M1A Resources and M1A Match at Camp Perry

Springfield M1A gunsmith armorer's course AGI

Do you own a Springfield M1A (or wish you did)? Then you should watch this 5-minute video from the American Gunsmithing Institute (AGI). This video shows the basics of the operation of the popular M1A rifle, the civilian version of the military M14. In this video, gunsmith John Bush field-strips the M1A and shows how the bolt, op rod, and trigger group fits together and operates. This video contains excerpts from the M1A Rifle Armorer’s Course, AGI Course #1584. The full Armorer’s Course is available on DVD from www.AmericanGunsmith.com.

Watch Highlights of AGI M1A Rifle Armorer’s Course:

Springfield M1A rifle camp perry m14 .308 win AGI

Springfield M1A gunsmith armorer's course AGI

2021 CMP Springfield M1A Match at Camp Perry

The 14th annual Springfield Armory M1A Match will take place during the 2021 CMP National Rifle Matches. The CMP will host the event on Sunday, August 8, 2021. Competitors of all experience levels are encouraged to bring their M1A rifles to Camp Perry and compete. CMP Online Registration commenced April 1, 2021. The match is open to all individuals ages 12 and above. For more information contact the CMP at competitions@thecmp.org or call 419-635-2141 ext. 724 or 714.

Springfield M1A match high power rifle

The Springfield Armory M1A match began with one man’s idea and passion. Springfield Armory’s Mike Doy witnessed the waning of classic M1 Garand and M1A rifles from the competitive High Power firing lines. “I really wanted to get those M1A rifles out of safes and closets and back out onto the field. So 11 years ago, I promoted the idea of running an M1A-specific match at Camp Perry. That first year we had over 600 competitors and spectators.” Now the match offers some of the biggest pay-outs at Camp Perry. In recent years, Springfield Armory has donated over $25,000 worth of cash and prizes, including a $2,000 cash award to the overall winner.

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April 1st, 2021

Can’t Find Reloading Powder? 1000 Grain Bottles Coming Soon!

DOT small powder bottles

We all know reloading powder is in VERY short supply these days. And the most popular propellants, such as Varget, H4350, and Reloder 16, are almost impossible to find at reasonable prices. Thankfully, there is a new solution in the works — smaller containers. This should give handloaders a whole new way to source those precious powders needed for a day at the range. And even if the volume is limited, something is ALWAYS better than nothing, right?

The big (and small) news for reloaders is that the major powder suppliers plan to start shipping powders in more compact, easy-to-ship containers. Instead of buying a pound of powder, you will be able to purchase an efficient, handy 1000 grain container. These are light weight (just 1/7th of a pound) so they are convenient to transport and carry. And you’ll never have the problem of over supply. A 1000-grain container with load approximately 33 6mm BR rounds — that should be plenty for a day at the range. We’re blessed to have this new compact powder option thanks to the U.S. Department of Transportation (DOT).

DOT small powder bottlesThe U.S. Department of Transportation (DOT) recently approved new smaller containers for shipment of smokeless powder. The new containers are designed to hold 1000 grains, exactly one-seventh of a pound. That works out to 2.29 ounces of powder — quite a bit less than you are getting currently with one-pound (16 oz.) containers.

Here how it works out:
7000 grains = 1 pound = 16 ounces
1000 grains = 0.143 pounds = 2.29 ounces

Many products — from cereal boxes to Snickers bars — have been down-sized in recent years. Now downsizing has come to the powder marketplace. The strategy behind the smaller containers is simple. In a market where demand vastly outstrips available supply, the smaller containers allow powder-makers to generate more revenue with a given amount of powder inventory. Will consumers accept the smaller powder containers? Probably so — 1000 grains is enough to load 20-22 rounds of .308 Winchester. In the current marketplace (with many powders virtually impossible to find), most consumers would probably prefer to get 2.3 ounces of their favorite powder, rather than nothing at all. (NOTE: The major powder suppliers will continue to offer popular powders in 1-lb, and 8-lb containers. The new 1000-grain containers will be phased-in over time, as an alternative to the larger containers).

Why the small bottles? One industry spokesman (who asked not to be named) explained: “We’ve had a severe shortage of smokeless powder for nearly two years. The powder production plants are running at full capacity, but there’s only so much finished product to go around. By moving to smaller containers, we can ensure that our customers at least get some powder, even if it’s not as much as they want.”

Why are the new containers 2.3 ounces rather than 8 ounces (half a pound) or 4 ounces (one-quarter pound)? One of the engineers who helped develop the new DOT-approved container explained: “We looked at various sizes. We knew we had to reduce the volume significantly to achieve our unit quantity sales goals. Some of our marketing guys liked the four-ounce option — the ‘Quarter-Pounder’. That had a nice ring to it, but ultimately we decided on the 1000 grain capacity. To the average consumer, one thousand grains sounds like a large amount of powder, even if it’s really only 2.3 ounces. This size also made it much easier to bundle the powder in six-packs. We think the six-packs will be a big hit. You get nearly a pound of powder, but you can mix and match with a variety of different propellants.”

Less Bang for Your Buck?
We’re told the new 2.3-ounce powder bottles will retail for around $11.99, i.e. about $5.21 per ounce. At that price, it may seem like you’re getting less bang for your buck … but hey, something is better than nothing, right?

DOT small powder bottlesCurrently, when you can find them, quality reloading powders are going for $45-$60 per pound (in 1-lb containers). At $45 per pound, you’re paying $2.81 per ounce. That means that the new mini-containers will be roughly twice as expensive as current one-pounders ($5.21 per ounce vs. $2.81 per ounce).

Along with the 2.3-ounce containers, the DOT has approved “six-pack” consolidated delivery units that will hold six, 1000-grain containers. Some manufacturers plan to offer “variety packs” with a selection of various powders in the 1000-grain bottles. Wouldn’t it be cool to have a six-pack with H322, H4895, Varget, H4350, H4831sc, and Retumbo?

Permalink Bullets, Brass, Ammo, New Product, News, Reloading, Tech Tip 8 Comments »
March 31st, 2021

How to Create A Dummy Round to Aid Barrel Chambering

Gre Tannel GreTan, Gre-Tan Rifles dummy round chambering gunsmith reamer chamber

How and Why to Create a Dummy Round
When you have a new custom rifle built, or a new barrel fitted to an existing rifle, it makes sense to create a dummy round. This should have your preferred brass and bullet types, with the bullet positioned at optimal seating depth. A proper dummy round helps the gunsmith set the freebore correctly for your cartridge, and also ensure the proper chamber dimensions.

Respected machinist, tool-maker, and gunsmith Greg Tannel of Gre-Tan Rifles explains: “I use the dummy round as a gauge to finish cut the neck diameter and throat length and diameter so you have [optimal] clearance on the loaded neck and the ogive of the bullet just touches the rifling.” He recommends setting bullet so the full diameter is just forward of the case’s neck-shoulder junction. “From there”, Greg says, “I can build you the chamber you want… with all the proper clearances”.

Greg Tannel has created a very helpful video showing how to create a dummy round. Greg explains how to measure and assemble the dummy and how it will be used during the barrel chambering process. Greg notes — the dummy round should have NO Primer and No powder. We strongly recommend that every rifle shooter watch this video. Even if you won’t need a new barrel any time soon, you can learn important things about freebore, leade, and chamber geometry.

Must Watch Video — This has been viewed over 764,000 times on YouTube:

This has been a very popular video, with 764,000 views! Here are actual YouTube comments:

That is the best explanation I’ve ever seen. Thank you sir. — P. Pablo

Nice video. You do a very good job of making this easy for new reloaders to understand. I sure wish things like this were available when I started reloading and having custom rifles built. Once again, great job, and your work speaks for itself. — Brandon K.

Beautiful job explaining chambering clearances. — D. Giorgi

Another Cool Tool — The Stub Gauge

When you have your gunsmith chamber your barrel, you can also have him create a Stub Gauge, i.e. a cast-off barrel section chambered like your actual barrel. The stub gauge lets you measure the original length to lands and freebore when your barrel was new. This gives you a baseline to accurately assess how far your throat erodes with use. Of course, as the throat wears, to get true length-to-lands dimension, you need take your measurement using your actual barrel. The barrel stub gauge helps you set the initial bullet seating depth. Seating depth is then adjusted accordingly, based on observed throat erosion, or your preferred seating depth.

Stub Gauge Gunsmithing chamber gage model barrel

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March 30th, 2021

Know Your Terminology — CUP vs. PSI

SAAMI CUP PSI Cartridge Copper Units Pressure PSI
Image by ModernArms, Creative Common License.

by Philip Mahin, Sierra Bullets Ballistic Technician
This article first appeared in the Sierra Bullets Blog

If you asked a group of shooters to explain the difference between CUP and PSI, the majority would probably not be able to give a precise answer. But, for safety reasons, it’s very important that all hand-loaders understand these important terms and how they express cartridge pressures.

The ANSI / SAAMI group, short for “American National Standard Institute” and “Sporting Arms and Ammunition Manufacturers’ Institute”, have made available some time back the voluntary industry performance standards for pressure and velocity of centerfire rifle sporting ammunition for the use of commercial manufacturers. [These standards for] individual cartridges [include] the velocity on the basis of the nominal mean velocity from each, the maximum average pressure (MAP) for each, and cartridge and chamber drawings with dimensions included. The cartridge drawings can be seen by searching the internet and using the phrase ‘308 SAAMI’ will get you the .308 Winchester in PDF form. What I really wanted to discuss today was the differences between the two accepted methods of obtaining pressure listings. The Pounds per Square Inch (PSI) and the older Copper Units of Pressure (CUP) version can both be found in the PDF pamphlet.

SAAMI CUP PSI Cartridge Copper Units Pressure PSICUP Pressure Measurement
The CUP system uses a copper crush cylinder which is compressed by a piston fitted to a piston hole into the chamber of the test barrel. Pressure generated by the burning propellant causes the piston to move and compress the copper cylinder. This will give it a specific measurable size that can be compared to a set standard. At right is a photo of a case that was used in this method and you can see the ring left by the piston hole.

PSI Pressure Measurement
What the book lists as the preferred method is the PSI (pounds per square inch or, more accurately, pound-force per square inch) version using a piezoelectric transducer system with the transducer flush mounted in the chamber of the test barrel. Pressure developed by the burning propellant pushes on the transducer through the case wall causing it to deflect and make a measurable electric charge.

Q: Is there a standardized correlation or mathematical conversion ratio between CUP and PSI values?
Mahin: As far as I can tell (and anyone else can tell me) … there is no [standard conversion ratio or] correlation between them. An example of this is the .223 Remington cartridge that lists a MAP of 52,000 CUP / 55,000 PSI but a .308 Winchester lists a 52,000 CUP / 62,000 PSI and a 30-30 lists a 38,000 CUP / 42,000 PSI. It leaves me scratching my head also but it is what it is. The two different methods will show up in listed powder data[.]

So the question on most of your minds is what does my favorite pet load give for pressure? The truth is the only way to know for sure is to get the specialized equipment and test your own components but this is going to be way out of reach for the average shooter, myself included. The reality is that as long as you are using printed data and working up from a safe start load within it, you should be under the listed MAP and have no reason for concern. Being specific in your components and going to the load data representing the bullet from a specific cartridge will help get you safe accuracy. [With a .308 Winchester] if you are to use the 1% rule and work up [from a starting load] in 0.4 grain increments, you should be able to find an accuracy load that will suit your needs without seeing pressure signs doing it. This is a key to component longevity and is the same thing we advise [via our customer service lines] every day. Till next time, be safe and enjoy your shooting.

SAAMI CUP PSI Cartridge Copper Units Pressure PSI

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March 28th, 2021

Forster Co-Ax Reloading Press Review by Erik Cortina

Co-ax Forster press
Forster Co-Ax Press

Forum member Erik Cortina has produced a series of YouTube videos about reloading hardware and precision hand-loading. Here we feature Erik’s video review of the Forster Co-Ax® reloading press. The red-framed Co-Ax is unique in both design and operation. It boasts dual guide rods and a central handle. You don’t screw in dies — you slide the die lock ring into a slot. This allows dies to float during operation.

Erik does a good job of demonstrating the Co-Ax’s unique features. At 1:00 he shows how to slide the dies into the press. It’s slick and easy. At the two-minute mark, Erik shows how sliding jaws clasp the case rim (rather than a conventional shell-holder). The jaws close as the ram is raised, then open as it is lowered. This makes it easy to place and remove your cases.

At the 5:20 mark, Erik shows how spent primers run straight down into a capture cup. This smart system helps keep your press and bench area clean of primer debris and residues.

While many Co-Ax users prime their cases by hand, the Co-Ax can prime cases very reliably. The priming station is on top of the press. Erik demonstrates the priming operation starting at 4:20.

Co-ax Forster press

Smart Accessories for the Co-Ax from Inline Fabrications
Forum member Kevin Thomas also owns a Co-Ax press, which he has hot-rodded with accessories from Inline Fabrications. Kevin tells us: “Check out the add-ons available from Inline Fabrications for the Co-Ax. I recently picked up a riser mount and a set of linkages for mine and love the results. The linkages are curved. When you replace the original straight links with these, the work area opens up substantially and the the press becomes much easier to feed.” CLICK HERE for Co-Ax Accessories.

Inline Fabrications Forster Co-Ax Accessories

Forster Co-Ax Curved Side Linkage
(For Better Access)

CLICK HERE

Forster Co-Ax Ultramount
(Riser plus Bin Support)

CLICK HERE

Co-Ax Roller Lever (Short)

CLICK HERE

Dual LED Lighting Kit for Co-Ax

CLICK HERE

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March 26th, 2021

Choosing the Optimal Neck Bushing Size — Tips from Whidden

John Whidden Dies Neck Bushing diameter reloading

Whidden Gunworks makes great sizing and seating dies. The Whidden full-length sizing die with neck bushing is very popular because it allows you to “tune” the neck tension by using different bushings, with larger or smaller inside diameters. In this video, John Whidden explains how to choose a the right bushing size for use with your neck-sizing and full-length sizing bushing dies.

For most applications, John suggest starting with the caliper-measured outside diameter of a loaded cartridge (with your choice of bullet), and then SUBTRACT about three thousandths. For example, if your loaded round mics at .333, then you would want to start with a 0.330 neck bushing. John notes, however, that you may want to experiment with bushings, going down a thousandth and up a thousandth. With thin In addition, as your brass ages and the necks harden, you may want to change your bushing size.

John Whidden Dies Neck Bushing diameter reloadingQuick Tip: Try Flipping Your Bushings
You may also want to experiment with “flipping” your neck bushings to alternate the side that first contacts the neck of the case. (One side of the bushing is usually marked with the size, while the other side is unmarked.) So try “number side up” as well as “number side down”.

Some folks believe that one side of the bushing may allow a smoother entry, and that this can enhance concentricity. Other people think they can get very slightly more or less neck tension depending on how the bushing is oriented. This is a subtle effect, but it costs nothing to experiment.

If one bushing orientation proves better you can mark the “up” side with nail polish so that you can always orient the bushing optimally. NOTE: We have confirmed that some bushings are actually made with a slight taper. In addition, bushings may get distorted slightly when the brand name and size is stamped. Therefore there IS a reason to try both orientations.

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