I've been loading for 20 years. Here's the problem. I'm loading .45 ACP for my Sig P220. I use various brands of brass, 185 grain Berrys HBRN bullets, set to 1.250 depth, 7.2 grains of Hodgdon CFE Pistol powder, with Lee dies, on a single stage Lee press. I'm getting blow back powder and occasionally stove pipe ejecting. I've tried no crimp, medium, and heavier crimps. No difference. I Amy the gun to Sig, and they replaced all springs, but found nothing when tested. Can someone help with advice or suggestions?