Re: Brass prep for precision AR15
Tumble, FL resize with a Redding Bushing die, trim to length with a Giraud (which also chamgfers and deburrs), uniform primer pocket, remove primer crimp if LC brass, deburr flash hole inside and out, nylon or brass brush the inside of the neck (brush chucked in a drill press for speed), Headstamp sort. Once brass prep is done - then the usual prime, weight each charge (RCBS Chargemaster), seat bullets and go shoot.
I tried sorting not only by headstamp but also by weight within 1 grain and I honestly didn't see much of a difference than if I just sorted by headstamp and they were all within about 3 grs. I get .4 to .75" 5-shot groups with a Larue Stealth using the above. I typically use LC08, LC09 or Win brass with 24.0 TAC/77 SMKs.
To speed up brass prep.... I use a Giraud for trimming/deburr/chamfer and then an RCBS case mate powered tool for the rest like removing military primer crimp, primer pocket uniforming, flashhole deburing, etc.