I learned the hard way to shoot a couple primers through before loading. I had cleaned the muzzleloader and must have had some oil residue or something left in the gun. It was about a -5 degrees that morning so I being cold I didn't shoot the primers through. That morning I had a very wide 6 pointer...could've been an 8 get to 35 yards, shot, primer went off, no powder went off, this happened a second time as I got the deer to stop at 60 yds voice grunting and took a second shot, again, the primer went off, but not the powder. After that I never went out without not shooting a primer first (usually I shoot 2 through) and then I load up. Haven't ever had a problem since.