Ok - a buddy of mine is helping a friend set up his Dillon 650 and was loading .223 Winchester brass on it with Hornady 55gr AMAX bullet (flat base bullet). When he seats the bullet it is more often than not crushing the shoulder downwards. It's not happening on each one but on most of them. I said that either he's got the neck tension too high (greater than 3 thou or it's the flat base bullet causing this problem). I bet a tapered base bullet like the 55 grain Nosler BT would fix the problem.
Anyone run into this and what causes it??
Anyone run into this and what causes it??