Istill think you should be using Real BLACK POWDER, instead of the sub. And, USE 2Fg to cut the recoil, not 3Fg. 50 grains of 2Fg is a mild shove, not a sharp crack to the shoulder or arm.
Also PUT A RECOIL PAD on that stock. They still sell slip over recoil pads, if you don't know how or can't do a fitting to the cut down stock. As long as he's not asking to run a .50 cal. RB through an Elk at 150 yards, the smaller loads recommended will work fine. But, recoil pads reassure young shooters that the " big gun " is not going to hurt them. A .50 caliber ANYTHING is a BIG GUN to kids, no matter how much they say they know about guns. Don't believe me? Ask your son how his NON-shooting friends react when he tells them he is going to be shooting a .50 caliber rifle for deer hunting this season!??
I get the reaction from kids in my Hunter Safety classes all the time. I PASS A Round Ball around just to get their eyes to come back down in size.
I also concur in recommending that whatever load you choose for him to use, have him to penetration testing, so he gains confidence that a well placed shot will kill a deer quickly. Phone books are okay. I use pine boards, so its easier to see the kind of damage a RB does, and recover the ball. This is going to be his first "REAL " deer hunt. There is a lot going on in his mind already, as he is also having to deal with killing a "bambi". It makes no difference how much venison he has eaten, or how many times he has helped you, or others clean or process a dead deer. This time, its going to be him. He doesn't want to disappoint you, and he doesn't want to be seen as a cry-baby who can't pull the trigger, or who becomes upset when he realizes he did kill a deer.
{HINT: Let the kid off the hook. Be there with him, and when he does kill the deer, have him stop and say a prayer of thanksgiving to God for allowing him to have this fine animal. It will give him something to do to deal with his feelings, and that will help him enjoy the hunt. Oh, if he does cry, tell him its okay. its all right for him to feel badly that he killed an animal so that he can participate in the entire hunting experience. I routinely tell my students that I cried the first deer I killed,( true!), that I was a lot older than they are, and that I still say a prayer of Thanksgiving to God for the deer's life. American Indians, for whom God was involved in everything they experienced, also said prayers thanking God for their successes in Battle, and in hunting.}
Good hunting for both of you. :thumbsup: