Category Archives: Arms

Understanding Gun Precision

I’ve written a number of posts over the years in which I test the precision of various firearms. Some readers have asked about the particular methodology I use.

When testing guns for accuracy it is common practice to look at the Extreme Spread of a group of 3 or 5 test shots. I will explain why this is a statistically bad measure on a statistically weak sample. Then I will explain why serious shooters and statisticians look instead at some variation of circular error probable (CEP) when assessing precision.

It is easy to fool yourself with Extreme Spread, and it’s even easier to fool others.
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Range Day

Over the winter I accumulated a bunch of new factory ammo, and a few handloads, I was waiting for a nice day to test. That day finally came! Suffice it to say that with four rifles, two of which I switched in the field from .338LM to also test .308, this was an all-day affair. Now I need to find time to analyze all the targets and radar data….

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Remington R51: My favorite new pocket gun

This Remington R51 is a really great gun. I bought it at the end of 2017 for $500 (including the Crimson Trace laser sight) while Remington was offering a $100 mail-in-rebate. I have to applaud Remington for going through the significant trouble of launching a pistol based on the Pedersen “hesitation lock.”

Previously, pocket guns with such a low profile were only available with simple blowback actions, which limits them to .380ACP or lighter cartridges. The R51 is rated for 9mm +P, which puts it in the realm of “full-power” defensive handguns. At one time I owned a Sig P232, which is a very slick .380ACP pocket gun, but I sold it some years ago during a caliber consolidation. Subsequently my only gun that really fit a pocket holster was the S&W 642 revolver. Lacking the cylinder bulge, the R51 is easier to carry in a pocket. If you’re looking for an “everyday carry” gun, you could end your search here on that basis alone.

S&W 642, R51, Sig P239

“Full-power” Sub-compacts: S&W 642, Remington R51, Sig P239

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Summit toggle action 10/22 now manufactured by Volquartsen

Interesting announcement today: The Summit toggle action 10/22 will now be manufactured by Volquartsen!

From the press release:

Dean Sylvester, PWS President and Summit designer commented “The Summit has been one of our most requested products over the years. We feel combining the unique features of the Summit design with the impeccable manufacturing standards and reputation of Volquartsen Firearms will allow both companies to focus on our core markets and ensure all customers are getting the best product possible.”

Hit by my own bullet!

Here’s a .22LR bullet that went through my paper target at 50 yards and then somehow ricocheted back to hit me on the forehead. (It then bounced onto the bench in front of me, leaving me scratched and bewildered, but nothing more serious.)

.22LR bullet that hit me

.22LR bullet that hit me

I’m well aware that bullets can do surprising things, and I’ve even researched some of them in depth. I’ve seen videos of people supposedly getting hit by ricochets of their own bullets fired into conventional backstops, but this is the first time I can offer a first-hand account of such an event.

I was doing more precision testing with a rifle in my machine rest, which meant that I was firing tight five-round groups very quickly. The last shot in one group made an unusual impact sound in the earthen berm behind the target, and as I lifted my head from the scope I heard a snap in the trees to my left and then something like a small pebble hit me in the forehead hard.

I was alone on a private range, and as I rubbed my head feeling for blood or a welt (and finding neither), I saw this slug on the bench in front of my machine rest. It was too hot to hold, so I set it aside while I finished shooting my test plan. After photographing it back in my shop I weighed it at 40.7gr, so if it shed any lead during its trip it appears to have made up for it by catching dirt in its crevices.

Does this story come with a lesson? Well, for one thing, wear eye protection! If this had hit me in an eye it would have produced a serious ocular injury. Another: Unlikely things can happen! I would still say it’s extremely unlikely for an unjacketed, subsonic bullet fired into an earthen berm to ricochet a full 180 degrees and cover another 50+ yards. (And, in that rare event, the bullet would not have enough energy to cause serious injury, unless it hit someone in the eye.) But however unlikely something may seem, just realize there’s probably somebody who’s going to have an astonished look on his face when it eventually does happen. Do what you reasonably can to make that the worst consequence!

Buckmark .22LR Pistol Accuracy, continued

Following some review of the recent Buckmark accuracy test, some readers wondered if the suppressor was hurting precision. Others, noting that Buckmark barrels are well known for their accuracy, wondered how the stock 5.5″ barrel would fare.

Buckmark pistol with Tactical Solutions 4

I ran the standard barrel through the same procedure as before. The aggregated data and analysis are in this Excel workbook, and the summary results with links to the 50-yard targets are here:

Ammunition CEP Radius (MOA) Average fps fps Standard Deviation
CCI SV 0.9 930fps   17.1  
Eley Contact 1.0 973fps   17.8  
Eley Club 1.0 958fps   13.5  
Gemtech 42gr 1.0 941fps   13.8  
Federal AutoMatch 1.2 1053fps   19.0  
Federal Champion HV 2.1 1073fps   20.5  

This pistol shot everything well. In fact, the best four loads tested would all be expected to hit inside a Bullseye 10-ring virtually 100% of the time.

Running the Tactical Solutions barrel without the suppressor seemed likely to help its score also, at least with some loads. At 4″, it gives up 40-50fps vs. even the 5.5″ barrel. But the accuracy of CCI SV went from CEP of 2.0 MOA to 1.3 MOA. Groups of Eley Club (essentially the same performance as Eley Target) showed CEP under 1.4 MOA. However, it was not able to tighten performance of the Gemtech load. (Detailed data were added to the spreadsheet from the previous test.)

Buckmark .22LR Pistol Accuracy

How accurate is a typical rimfire pistol? Out of curiosity I mounted my Buckmark, with its 4″ Tactical Solutions barrel and 5″ AAC Element II suppressor, on my test stand and recorded shots simultaneously at 25 and 50 yards.

Buckmark pistol with suppressor in test stand

As usual, I digitized the paper targets using OnTarget TDS, and followed the statistical analysis outlined at ballisticaccuracy.com. The aggregated data and analysis are in this Excel workbook.

Ammunition CEP Radius (MOA) Average fps fps Standard Deviation
SK Plus 2.0 904fps   20.0  
Eley Target 2.0 952fps   11.9  
Gemtech 42gr 2.0 910fps   15.0  
CCI SV 3.1 914fps   16.2  
Federal Champion HV 4.7 1037fps   14.6  

I was surprised at how much more dispersion this gun shows than the 10/22 rifles I have tested. It’s certainly nothing to brag about: The 10-ring on NRA Bullseye Pistol targets (shot competitively with autoloading rimfire pistols) typically has a radius of 3MOA, and even with zero shooter error the good ammo here would only hit that 80% of the time.

How to hold a small pistol with large hands

I was training a woman for precision rifle shooting when she showed me her defensive handgun: a S&W M&P Bodyguard 380. This is a very small pistol: 5.25″ long, 4″ high, and just 0.75″ thick! Its dimensions make it easy to carry concealed, but can make it tricky to shoot.

This woman’s hands are almost as large as mine (which are 8″ long and 3.5″ wide mid palm), so I asked to see how she was able to handle such a small gun. Through practice on her own, she had concluded that even though she is both left-handed and left-eye dominant she shot it better with her right hand. Since it’s a double-action-only gun with a long, heavy trigger, she had resorted to pulling the trigger using the second knuckle. She noted that doing this she would often hit the magazine release with the tip of her trigger finger, but she didn’t know how else to run the gun. She also couldn’t figure out how to get her support hand on the gun, and so she presented it with the largely ineffective “teacup” hold.

The same guidance for holding guns that fit can be applied to holding undersized guns. Of course, the first order of business was to nix the idea of pulling the trigger with anything other than the center of the first joint of the strong hand’s index finger. (With large hands it can often be necessary to arch the trigger finger outward, but you never compromise on this point.) Then I showed her how to follow the usual steps of establishing a proper handgun grip:

  1. Push the firing hand web between the thumb and trigger finger as high on the grip as possible.
  2. Find a “home” position for the trigger finger outside the trigger guard, and then close the remaining fingers and palm snugly around the grip.
  3. Now snug the support hand up and around the gun and trigger hand in order to maximize contact with its palm and fingers.
  4. Ensure that the support thumb and index finger don’t interfere with the gun’s controls or the trigger pull. (Typically the support thumb will rest parallel and ahead of the trigger hand’s thumb. The support index finger needs to find a home too, and while that is often atop the knuckle of the trigger hand’s middle finger, on some guns it can instead find a consistent grip on the front of the trigger guard.)

Chronos High Speed Video Camera for Shooter Diagnostics

Today I’m going to show a project that exploited the Chronos 1.4 at high image resolutions and at the lower end of its temporal resolution (i.e., frame-rate): What does handgun recoil look like, and how can a shooter control it?

I took a rusty shooter to the range with his Sig P239 chambered in .357SIG. This is an excellent concealed carry gun shooting arguably the ideal cartridge for defensive handguns. However, since the fully-loaded gun weighs only two pounds it has somewhat snappy recoil which requires training and practice to handle well.

Stepping through the video frames we can see that this pistol’s “lock time” (the delay from when the trigger is pulled until the hammer hits the primer) is 5ms. Also, from the moment the trigger is pulled, it takes 18ms for the slide to cycle to the rear, and 63ms to return to battery.

We filmed the shooter’s first few shots. He had forgotten some pistol fundamentals, including: proper grip, not anticipating the recoil, and following through each shot. (Granted, most of these problems can be detected or assumed even without high-speed video.) After retraining we filmed a few more shots. The improvement was remarkable. Beginning the refresher the shooter experienced muzzle flip of 40 degrees and consistently took over 60ms to halt the recoil of the gun. This composite overlaying the moment of discharge with peak recoil shows the slide already returned to battery by the time the shooter has stopped the recoil:

Recoil composite before retraining

After retraining, the shooter was able to keep muzzle flip under 20 degrees and stop the recoil in under 40ms. (This was accompanied, of course, by faster and more accurate shooting.)

Recoil composite after retraining