I will tell you my experience(which is limited) with a Rossi .243
/.50 cal muzzleloader. A friend loaned me one for my 10 year old son the 3rd week of November. We had 2 light primer strikes on a 60 degree afternoon. I'm not sure if it was the ammo or the rifle.....it looked to me like it was over oiled.....after a thorough cleaning it has been fine, so I can only assume it was the oiling.