Not sure I'll have to check that. By factory I mean I purchased factory loaded ammo and the case bubbles I found were all from those. Not resized. not reloaded. by factory I mean factory, by reloads I mean reloads.
The only reloads that have done this are 1 fired brass where the original firing was a factory purchased cartridge. not put together by me.
Apologies for being unclear I'll back up to the beginning.
I first noticed this issue when firing my load development reloads. These cases were once fired (I buy factory loaded ammo because for the cost of brass up here its cheaper (and more fun) if I get to shoot it once. The seating depth for these isn't dictated by chamber but instead by magazine length. I ladder test for load development first by jumping up half a grain at a time (usually starting about 10% above minimum recommended load) then Honing in my load in .2 gr increments till I find the preferred one. I'll try several bullet and powder combinations during this. The first instance of this happening was at 40.5 gr of IMR 4166 with a 175 gr SMK.
Now all of this Hornady brass was once fired in the AI AT originally but FL sized which I then used for load development in the DT. I don't have a measurement for how much of a shoulder bump this brass got because quite frankly I've never measured or had the tools to measure. How I was taught to reload is keep it simple and the 1/4 to 1/2 MOA results I've been getting have been adequate for my uses. The process I go by for FL sizing using is set the die by using the locking ring. This position is to raise the shell holder, touch the base of the die and then back it up a 1/4 turn and lock in place with the set screw on the locking ring. That way its in the same place every time. I realize I could definitely get more technical and wanting to try some PRS next year, I probably should look at neck tension and shoulder bumping more closely. I've sized all my brass this way from .223, 6.5x47 Lapua, 6.5 Creedmoor, 260 Remington, 300 win mag, 300 PRC, 300 norma and 338 Lapua and never had an issue like this before (I understand that just because I didn't experience an issue doesn't mean there isn't a problem).
Once I started the thread on here I then went into an in depth analysis of all my brass, I checked the inside of cases with the paper clip, inspected ALL brass, once fired, and twice fired. The ONLY ones I could find with issues prior to my chamber being damaged were the Hornady brass. Which I believe the majority were damaged in the AI (if not all). These were all factory cartridges that were purchased in a store and not reloaded.
Where my problems originally stemmed from I believe was the AI rifle. I think the headspace on that rifle was indeed long as some of you had said on here, and I never noticed the brass being damaged. I also will say I never checked thoroughly enough because it was factory brass.
That inaction cost me the chamber on my DT. As it has a definite line on it that will damage brass from here on out.
Some of this brass was from my previous 308 rifle (an AI AT) which I hadn't noticed any issues (doesn't mean it wasn't happening.)
I think going on from here I'm going to throw out all the brass fired in the AI ( I don't want to take the risk) and buy new. This definitely opened my eyes to head spacing/ shoulder movement and I'm going to keep my eye out for that going forward.
I also think that
@TheNatural21 is correct in saying that I can't use the brass from the AI in anything else. I'll be sad throwing out 200 pieces of brass. Good thing I just have the DT left.