I've used Hornady, Lapua (srp), and Alpha srp. Haven't had any issues. I wouldn't advise running 43 grains of H4350 though, that's fairly hot. I mainly use srp just because my gun craters lrp pretty bad just since it's not bushed. What lead you to decide to run 43 grns. Did you work up to that or just say hold my beer were going in? How many loadings did it take to blow out the primer pocket?