Blair,

I am still working up loads for my 577-3" BPE but so far I have used Dacron, kapok, and foam backer rod for filler material all with Federal 215 primers and H4198 powder. I have never experienced ignition problems with these loads. My best load so far is a 605 grain 20:1 hollow based paper patched bullet with 73 grains of H4198, 1.6" of 5/8" foam backer rod material, and Federal 215 primers. When I have results that I'm happy with accuracy wise, I will post my findings. I have also tried Goex Express 1F, Swiss 1.5F, and Swiss 3F black powder loads but none of them were very accurate so I decided to work on the NFB load first and then tackle the black powder loads later.

Shoot straight,

Jim