For quite some time I have heard from shooters on various forums and even some first hand accounts of ammunition that was repeatedly cycled through a handgun. Example given, a shooter arrives at the range and downloads defensive ammunition and loads target ammo commencing range session. Once the range session is complete the shooter loads up defensive ammo and heads back out on the street. Over time the shooter may cycle the top one or two rounds through the chambering/unloading process dozens or even hundreds of times depending on frequency of range sessions and carry ammo change out. The hypothesis was that cycling the round into and out of the chamber repeatedly caused the primer to fail.
Having never experienced a failure of this type on my own I decided to try and make some ammo fail to get an idea of the legitimacy of the issue and find out how I could avoid exposing my ammo to forces that may prevent it from functioning. I started with a box of some fairly common ammo, Federal Range and Target 115gr 9mm. I shoot quite a bit of this ammo along with two other brands, Magtech and Independence. Not for any particular reason other than local supply and price point.
I started by marking the internal plastic organizer of a box of 50 rounds with the numbers 1, 5, 10, 15, 20, 25, 30, 35, 40, 45. This was to be the number of times I would cycle that row of 5 rounds through a gun and then take the box to the range and shoot each round to find any failures. I commenced the process of loading a mag, cycling the rounds, tallying the cycle, reload, repeat. Once I got to the row that exposed the 5 round sample to 30 cycles into and out of the chamber I noticed a significant amount of projectile setback in the casing. For this reason I did not continue to cycle sample rows 35, 40, 45 as no solid data would come out of rounds with enough set back to be of concern to fire.
I went to the range today to run through the box not sure what to expect. Based on reports, I somewhat expected most of the rounds to fail. I was pleasantly surprised that there no failures in the rounds fired. I did not fire the rounds with major projectile setback.
Rounds organized for cycling and firing.
All test firing and cycling was performed with a Glock 17 Gen 3 with a factory barrel.
Two rounds from 30 cycles sample shown with significant projectile set back.
Look for a similar test on some other brands and types of ammo. Overall I am happy to say this ammo did not fail to fire and the projectile setback didn’t occur until extensive cycling. Even still, projectile setback is an easily identifiable change in the ammo as opposed to a failed primer that is functionally impossible to identify short of dismantling or firing the round.
Moral of the story, change defensive ammo regularly and visually inspect all defensive ammo for negative characteristics as you load your mags up.