Quote Originally Posted by killforfood View Post
I’m not talking from experience but won’t these heavy walled Jamison cases need a full load to fully fire form on the first shot? I don’t mind a stiff load. I bought one of those old Steyr Mannlicher M95 rifles that Big 5 was selling. It took me awhile to find some old Nazi crap to shoot in it but boy did those old loads put some wood to my shoulder, and a smile on my face.
Essentially you do not want empty space in a BP cartridge or you could risk rupturing the case and/or ringing the chamber, if not blowing up the gun. With some calibers, it's not an issue if you just fill the case minus the volume of the bullet, but you would still use a card and preferably a small grease cookie to keep the fouling soft. Patrick will likely cover that later.

I'm not sure if .43 Mauser is one of those rounds that requires filler or not. I shoot a lot of .577-450 and you DEFINITELY need a filler. Filling a modern extruded case would likely grenade a martini action.