Does not say, but I'd guess a Sierra Matchking? Great ballistics, but I have zero experience with that bullet, but know some guys use them for hunting. But if my guess is right, I'd vet that choice with reliable hunting field reports or find a bullet designed for hunting, before using it on anything much larger than deer. Hopefully a member or two on the forum has experience with that bullet on game, I don't. Or did the gunsmith say it's OK for hunting based on their experience, not just for punching holes in paper. Not trying to create doubt, but I'd want to know what bullet they are using to establish comfort before hunting with it.