Interesting test. Other powders likely respond differently to changes in seating depth. If you do more testing along this line, maybe try a faster powder to compare.

Bullet setback from chambering is a real concern and definitely something to keep an eye on. With expensive defensive ammo, when possible I chamber a round using a separate magazine. Having only a single round in a magazine reduces the pressure against the mag\’s feed lips and prevents scratching a round below. I also somewhat ride the slide forward, which normally you don\’t want to do. This eases the round into the chamber and minimizes dings.

Good advice about using a thin Sharpie to mark bullet position in relation to the case neck. Do that and/or occasionally measure your repeatedly chambered round and compare with unused factory ones. I\’ve set a few aside that had shortened some. My reloads often seem to have better hold on the bullets than factory rounds. I often wonder if I\’d be better off using cheaper ammo for defensive purposes so I\’d be more inclined to cycle through it more frequently.

In guns with floating firing pins, the AR being a common example, don\’t repeatedly chamber defensive or other serious ammo. The firing pin contacts the primer each time a round is chambered. Once isn\’t a problem, but repeated taps can damage the primer. There are horror stories about this. The last thing you want when your life is in danger is to get a click instead of a bang when you press the trigger.

On a similar note, another caution is about storing guns in vehicles. Some people have a \”car gun\” or a \”truck gun\” that lives full time in the vehicle. Others are forced to leave their guns in cars while working, etc. I live in the desert, and vehicle temperatures here get insanely hot in the summer. One summer I had to leave my pistol in the car each day while at work. It was parked in full sun. Late that year I became concerned about the ammo being exposed to so many temperature extremes and swings. I know such things are bad, but at what point does it actually become a problem? I don\’t know. I somewhat reluctantly fired all of the factory 124 Gold Dot +P rounds in the pistol as well as all in the spare mag that had been carried with it. They all worked fine. It was an expensive test.

During that shooting trip a friend thought I was being overly concerned about my ammo. He had kept a loaded 1911 in the console of his truck for 2-3 years without changing ammo or firing the gun otherwise and was confident everything was fine. I convinced him to try it. His first shot was a dud. Click, not bang. I wish I had a picture of the look on his face. This pistol was what he would have reached for to save his life. The firing pin strike was normal, but the primer didn\’t ignite. He had at least one other dud in that magazine of ammo, maybe 2 more. I don\’t remember what ammo he was using. It was factory, and almost certainly good stuff. I\’m thinking most likely factory 230 grain Gold Dot.