I have a book by Don Davis, Muzzleloading... to begin with,where he teaches the basics of muzzleloading through his flintlocks and all the things one needs to know as to how to load, hunt, shoot, possible bag, etc. In the book he mentions his friendsfavorite deer load out of his Kentucky long rifle as 50 grains of powder and a roundball. He limits his distance and says with that load it puts that ball well into the kill zone were the ball can then release all its energy. There is a school of thought that says pass through is not all that important. It is the damage of internal tissue and the release of as much energy from the projectile to the body cavity. I personally do not believe that school of thought. I like pass through, but have seen a lot of deer killed without a pass through shot being made.

I think 50 grains of Triple Se7en and the 240 grain XTP will work just fine. Especially with the limits you have set for your son in the distance department. Have him place that behind and not through the shoulder blade, and he should be just fine. Actually at those lower velocities, a standard XTP made for a handgun might get some excellent expansion and do some rather impressive internal damage. I would not look for a pass through by any means, but you can never tell. Just watch the deer after the shot, the direction it runs, etc. It should not make it far if your son's shot is true.