Re: When to discard brass
Ignore the dents, they will blow back out when fired, it's part of the fireforming process.
Brass needs to be retired when at least one of several conditions appear. The first one is harder to find, it is the internal ring-groove that appears where the case wall thins out to sidewall thickness just above (about 1/4" above with .223) the extraction groove. You find it with a feeler made of wire with a short (1/8") right angle bent into the tip. Cases with such a groove are DRT (Donefor Right There), the groove is the Imminent Precursor to a Case Head Separation.
As brass gets fired/resized, fired/resized, etc., etc., the brass gets worked back and forth, especially in the neck. This hardens (called work hardening) it making it too brittle to stand up to the natural expansion and contraction that occurs during firing. Eventually the necks split and the case needs to get tossed. When this is getting ready to happen, you will note increased resistance to the neck sizer ball, and more required force when seating bullets. This resistance indicates increased work hardness, which can also mess with neck tension and degrade accuracy. This can be 'reset' by annealing the necks. I don't anneal, so when a few cases from a lot split, I retire the rest of the cases by loading them up with a hunting load for one last cycle.
Finally, as cases get fired, especially with 'warmer' loads, primer pockets tend to expand. Eventually, the same work hardening process will defeat their ability to contract back down to normal diameter, and primers will not seat with enough resistance to function properly. When primers 'fall' into the pocket, they are usually too loose, and may even fall back out when the case is picked up. This is usually the death knell for cases, but there are some aftermarket processes which can be employed to swage the primer pocket back to a useful diameter. Never, never, never, ever, ever, ever anneal case bases; 'bad things' will happen.
Greg
