The Cornered Cat
A slight setback

Came home from a long day, getting ready for bed. Pulled my holstered gun off my belt and locked it into the quick-access bedside safe — yep, still in its holster. Still loaded. It’s secure, and also ready to go should I need it.

I’m not a big fan of unnecessarily unloading and reloading my carry gun.

Why not?  Because I don’t want my ammunition to suffer from setback. And because I do not want to risk killing the primer without knowing I’ve done it.

 

The round of ammunition on the left is healthy and the length it should be. The one on the right has suffered a slight setback.

The round of ammunition on the left is healthy and it is exactly the length it should be. The one on the right has suffered from setback, making it significantly shorter.

 

As you load a round of ammunition into a semi-automatic gun and then remove it from the chamber without firing, the bullet naturally tends to get pushed back slightly into its case. When this happens, the compressed powder can 1 create much higher pressures inside the chamber than the gun is designed to handle. The result can be a bit … messy. Also expensive and painful.

Loading, unloading, and reloading the same round can also cause the primer mix inside the case to get knocked out of place, a problem you won’t be able to see by looking. But the missing primer mix means the round simply will not fire when you need it.

When a self-defense gun fails to fire, the results can be catastrophic for the person who was relying on it to save their life.

What to do about this? I love this advice from Chuck Haggard of Agile Training and Consulting.

“If you simply must unload/reload daily … I strongly urge you to not re-chamber the same round more than 2-3 times, and to keep track of this to mark the round coming out of the chamber with a Sharpie so that you know how many times it’s been chambered. A tic mark on the rim of the case is easy to do, and easy to see.”

This seems to be an easy solution. Avoid unloading and reloading your gun whenever possible. But when you must, keep track of how many times you’ve done it. Simple.

Summing up:

  • Avoid loading, unloading, and reloading the same round multiple times.
  • Keep track of the number of times one round has been through the process by putting a small mark on the side of the case each time it comes out of the chamber.
  • When one round has been loaded and unloaded more than a handful of times, take it to the range and shoot it during practice. Do not continue to load and unload that round for self defense.

One round of ammunition costs around 50 cents. One new handgun costs around $500. And one life is priceless.

Stay safe.

Notes:

  1. Note the word can. This is not to say it necessarily does, in every case. There are informal but popular “research” papers that say this isn’t a big deal, on the basis of one backyard test with a hammer and no way to measure the pressure inside the round. But on the other hand there are also many, many first-hand reports of setback being a factor in exploded guns, including several that come from law enforcement agencies that investigated multiple incidents. And there are even graphs and things that explain the science behind this. (Also see: Normalization of Deviance.) A single exemplar of a gun that failed to explode as expected does not overcome the weight of experience and the science that says setback-induced overpressure can indeed be a factor to respect.

5 Responses to A slight setback

  1. Pingback:A slight setback — Cornered Cat | WyldKat's Lair

  2. BTPost says:

    If you are getting significant setback, you need to advise the Ammunition OEM, so they can adjust the taper Crimp on their Seating Dies…

    • larryarnold says:

      As I understand reloading, taper crimp is used mainly on revolver cartridges.

      With most semiauto cartridges the mouth of the case seats in the chamber to create the correct headspace. The bullet is held in place by friction between the side of the bullet and the inside of the case. Tapering the mouth of the case would let the cartridge go too far into the chamber.

      Note the cases in Kathy’s illustration, which are not crimped.

      Revolver cartridges headspace on the rim, so they can be taper crimped.

      YMMV

  3. BTPost says:

    A Taper Crimp, when done properly, will NOT change the Head Spacing of the Cartridge, but WILL add to the Friction of the Case to the Projectile, and keep the Projectile from Significant Setback…. The difference IS in how the Seating Die is adjusted, and can be measured in single digits of ten-thousandths of an inch, between the beginning and end of the Taper Crimp…. and the amount of friction in Inch-Pounds of force required to move the Projectile…

  4. Pingback:Weekend Knowledge Dump- February 16, 2018 | Active Response Training

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