Originally Posted By: AlecThanks for the responses All. Although I have never owned an auto load rifle before,except a 10-22, and thus disqualify myself as an expert an the crimping subject I have loaded for bolt actions for almost 40 years now. And do have an opinion as thus : the recoil on a 223, especially a gas operated auto, is way less then the other rifles I load for. I have never crimped on an rifle reloading before. The amount of contact the cases neck has is a lot, a 60 grain bullet with an OCL that dictates full contact the entire case neck length is a very firm grip. bullets heavier then the 60 grains might dislodge easier in the magazine with heavy recoil. It doesn't sound like AR reloaders like to seat bullets .0010 off the lands like bench rest guys, I guess its because of action cycling issue. Full length sizing and not neck only eliminates the possibility of the neck be sized only part way down, and should eliminate jam problems that might ruin bullet alignment or OCL. The idea that crimping could improve group size, in my opinion, doesn't hold water, but certainly could happen for some. I think I'm going to order a set of RCBS 223 competition dies for this gun with the intention of not crimping. thanks again Alec Nemon Not loading .010" off the lands is more of a what COL will fit in the magazine.The idea of crimping improving group size, as claimed by Lee Die is a more uniform starting pressure.I have used a(hammer type)puller to pull an uncrimped bullet and I can agree crimping is probably not necessary.