Re: reloading brass fired from AR platfrom
Some of the general tell-tale signs from those of us loading bulk quantities for 3-gun style shooting is that we continue to load until there's easily noticeable problems: loose primer pockets, split or very thin case necks, very hard brass to resize since most of us don't anneal, or odd case indentations (usually not reload related but cause us to discard them none the less). A lot of the 3-gun shooting is closer in (the matches in my location hardly ever get out past 100yds) so many of us run fairly light loads (for instance mine is typically a 55FMJBT over 23.5 of H335, which gives me an average of 2777fps with a 52.1fps SD). This is nowhere near match prepped ammo for bolt action style shooting. While I have not checked each case for incipient case head separation, from what I have seen so far you will notice loose primer pockets or split necks much sooner.
I am sure some of the other guys will chime in here with their brass life shooting match grade reloads from AR/gas platforms.