An anecdote about bullet setback and accuracy

I have to make an embarrassing confession: I don't cycle out my carry ammo. I know, I know - this is not a "best practice". But I tend to buy this very good stuff on this very tight budget, hence the handloading to allow practice with comparable performance on the cheap. So... out comes the mag, cleared is the chamber and the same rounds get loaded back in once I'm done. I really didn't think about the long-term ramifications until my latest range session with the DB380.

Deb had picked up some factory .380 at my request and, since I was now flush with mass-produced cartridges, I decided to use the Diamondback to burn up the old factory ammo I'd been carrying in my KelTec for the past few years. See, um, the cases were looking a little worn... and discolored... maybe a little "bumpy" at the case mouth. Yeah. I'm generally a safe guy especially around firearms but this was out-and-out stupidity on my part.

(For the record, no mechanical hiccups or failures were encountered, further reinforcing my belief that the previous problems were user error and/or hard primers. )

I set up the target, paced out about seven yards, took careful aim and - bang! - fired way low and left. Hm - that's odd. Maybe I jerked the trigger, a mild case of the "haven't shot in a bit" jitters. Let's take a breath and try it again. Bang! Off the paper. Seriously?!? I continued on and printed more of a pattern than a grouping, having eventual (and only moderate) success in dialing in by holding high and right about five inches. This is when I started thinking about bullet setback and all those rechamberings.

I loaded up the brand-spanking-new rounds and decided on a six o'clock hold again rather than staying high-right. Three full magazines of rapid-firing later, I had a ragged, three-inch hole on and barely above the aiming point I'd marked. Same distance, stance and grip but I still achieved better results even when using a hastier pace. The only difference was the condition of the ammo.

Now, this is purely anecdotal and hardly scientifically quantified but a coincidence worth noting. I haven't examined the spent cases (yet) for any signs of overpressure but this seems to be circumstantial evidence that case wear and tear adds up over the years. Performing a few searches on "bullet setback" returned hits mostly about dangerous chamber pressures but nothing to speak of in terms of accuracy. It makes sense that an increase in pressure combined with a pretty truncated launch tube might affect accuracy to a notable degree (worth a moment of pause, there, given how critical placement is when using a "mousegun") but I can't really say I've got enough evidence to make more than an anecdotal post on a personal blog :). If anyone reading this has noted similar behavior, regardless of caliber, I'd be interested in hearing about it. I'm going to try to run a similar test with my Glocks' Gold Dots (9mm and .45ACP) and will post an addendum if I get the same results.

Now I need to get back to work so I can afford a few boxes of Gold Dots to replace the ones I need to burn up for the Glocks....