Assuming a jacketed bullet and a lung shot he will do ok,I have taken a number of deer with a 44 mag and no problems and thats what that load is comparable to. Full lenght body shots should be avoided,but most of us do that anyhow.If he is shooting a slow twist barrel he might try the 200 gr bullet with a little more powder , he should check his operators manual for max load and since a 50cal. ball is 180 a 180 or 200 gr bullet might give good results.Lee