I was getting misfires in my 577 bpe. The primer drives the bullet,wads and powder about 6 inches into the barrel.
The load was 64 gr. of 4198, 215 primer and a 520 gr. paper patched bullet. I tried wads of dacron, foam, and felt to no avail. The only solution I have found is 2 gr. of unique under 62 gr. of 4198. I use foam wads because of their convenience. This load regulates in my rifle and was good enough to take a small white tail at 100 yards.

Dave