JTT: Ammunition, Chambering, Checking, and Problems

| March 7, 2017
Categories: Learnin'


Just The Tip: Ammunition, Chambering, Checking, and Problems

Richard Kilgore

While it’s unlikely that we get to choose the time and place of a gunfight unless we’re the aggressor, there are certainly some things that we can control, and care of ammunition is one of them. This piece isn’t so much about what kind of ammunition to use, but how to ensure that whichever defensive rounds you choose have the best chance at ignition (and hopefully successful target penetration, preferably making a solid CNS hit). With that in mind, we bring a pair of tips foraged from the great wide world of the internet. Except this advice isn’t coming from rando gun forums, but people that we know and respect. Without further ado:


Claude Werner, The Tactical Professor shared this on his Facebook page a couple days ago:

I was asked about the system I use to make sure duty ammunition doesn’t get chambered excessively. This is important for people who unload their pistol daily because of children in the home. Priming compound can disintegrate when chambered excessively. A local officer found this out the hard way. Fortunately, he was not injured in the confrontation.

The system is simple. The base of the cartridge gets a mark before I chamber it. When it has four marks, it goes to the bottom of the magazine. When all the rounds in the magazine have four marks, I shoot it up and reload the magazine with fresh ammunition. There’s no magic to the number four. It’s just what I picked.

The round on the lower right in the picture was just in the chamber. The rounds with four marks go in the magazine with the unmarked round on top of them. The round with one mark gets another mark and goes on top to be chambered. This magazine is almost done.


If you take the round out of the chamber every day, with this system, you’ll have to shoot the magazine every two months or so. Officers who carry two spare magazines can make their issue ammo last about six months by rotating the magazines in their pouches.

You can also see Claude’s writing online at The Tactical Professor webpage.

But even if you don’t physically unload your weapon every night, you may indeed perform press checks. Aaron Cowan of Sage Dynamics did some testing years back that involved calipers, Hornady ammunition, and a whole helluva lot of press checking.


Here’s a brief rundown with some excerpts:

So what does a Press Check do in regards to the ammunition? As we pull the slide (or the bolt, in the case of rifles) to the rear in order to see the round, we unseat the round from the chamber and drag it rearward to a point where we are certain we in fact see a round and then the slide (bolt) is either ridden forward or let forward under spring tension. The question is; does this hurt the round and can it lead to a malfunction? The answer to both is yes, it can.

Using three Critical Duty Flexlock rounds, I press-checked one round 200, one 300 and one 500 times (using the method pictured above) in a Gen 4 Glock 17 (also pictured). Before beginning this process, I measured each round with an electronic caliper. After a week of working press checks to my desired numbers, I measured them again. They were shorter than before. This was a simple and straight forward experiment that may not satisfy the desire for complete scientific controls, but it serves as a strong anecdotal experiment that lends to my opinion that press checking can be harmful and is largely unnecessary (we will get to the last part).


So what does this prove? Well, a bullet seated too deep in a casing will create over-pressure when the primer is stuck and the powder ignited. As the powder burns it releases gas, which presses in all directions inside the cartridge. As the bullet is designed to separate from the cartridge and there is nothing stopping it from being propelled down the barrel, you have a successful discharge. With a bullet seated too deeply, you have the risk of the cartridge fracturing which may simply result in a cycle malfunction, a squib (bullet lodged in the barrel as too much energy escapes via the cartridge rupture before the bullet can be forced out of the barrel) or a chamber rupture.

Bullets seated too deeply in casings have been known to destroy guns and pride. It is also possible that repeated impacts into the chamber as the round is reseated can cause the primer mixture to work out of the primer, which means the round will not fire. Does this mean your press checking is going to lead to a catastrophic weapon failure? No, it’s not guaranteed. However, it’s avoidable as the press check is pointless in 99% of situations.



Before sure to read the entire post here and you can checkout Sage Dynamics online here.

-Swinging Dick

Mad Duo, Breach-Bang& CLEAR!

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  1. American Patriot

    I never need to press check cuz the only times my carry gun is Not chambered is when I fired the last round & it’s in slide lock or disassembled on my bench for cleaning!

    I also always measure my ammo in my carry gun, the entire 50 rd box of Gold dots 124gr +P & there can be up to a .020 difference in length. I reclean & oil my carry gun on a monthly basis & measure the chambered rd every time I remove it & record the measurement in my monthly reminder.

  2. Jeff

    “When all the rounds in the magazine have four marks,..”

    Why in heaven’s name would anyone play with his gun and ammo this much?

  3. Ordnance Marine

    This is a great reminder.

    I have been plinking “chambered” ammo for years. It is cheap and gives peace of mind. Goob job.


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