Re: Neck sizing for an AR?
I have reloaded for a 6.5 Grendel and I can tell you from personal experience that each and every case must be full length re-sized. I had to pay particular attention to insuring the full length sizing die completely bottomed out. The result in not doing so is a round that will chamber but not fully. The bolt assist will not help either and the result is a stuck round. The best way to clear this is not with a mallet, as suggested above, but just slam the butt on the ground or anything solid. This allows the weight of the bolt carrier group to do all the work. Good luck.