Although not that much of a problem in mini's or bolt actioons, but since we are talking AR's, and since they utilize a free-floating firing pin, new Winchester primers tend to slam-fire after the bolt is released. They are aware of this problem, as the cup is quite soft.Originally posted by Deputy Al@Dec 24 2003, 12:12 AM
I have used AR's 69 MK/25.0 WW-748 load since the bullets hit the market, and they just drive tacks--even in Mini-14s. Once "secret" to success with ball powders like 748 is to use W-W primers with them--these apparently have an aluminum oxide additive in the primer mix that does good things with ball powders. As always, work the load up in YOUR rifle from 10% below.
One good tip is to use Rem 7 1/2 primers--benchrest primers for a good price (less than Fed Gold Medal)