A suggestion.........For years , I use a trap shooting right arm/shoulder position. That being the right elbow /arm , raised up at a 90 degree right angle to the right side of the body. The left arm firmly pulls the butt back into wherever the butt plate is anchored. Over the years , I've had to adjust a couple military trained shooters in the ways of shooting muzzleloader rifles. Usually , this method is surprising to them , in that off the bench , they don't get smacked in the face with the rifle's comb. Also , large caliber rifles over .50 , are not the norm for mountain rifles. Some thoughts....