The 90gr. BM3 load behind a 300gr. Hornady SST bullet is enough for elk and the recoil is where I think your son can handle it. I am only 150lbs and I do not like heavy recoil. I shoot a 7X57 for elk instead of my 30-06 just because I don't like the 06 recoil and my old military 7X57 mauser rifle actually outshoots my 06. Unless you run into a really big bull the 300gr. bullet will do the job if you put it in the right place. It also shoots the 295 Powerbelt at almost the same point of impact so it makes a good follow-up bullet as it loads a lot easier than the SST. I sure wish Magkor would get on the ball and get their distribution going.