I have to agree with MD, in that I have never seen a youth model huntsman. I would suspect that a hardcast 200ish gr. bullet will punch clean through whatever deer you are shooting at. Just make sure that it has a wide meplat to cut a nice hole to bleed out of. I am going to use a 260gr. cast with 80-85gr. of T7 this year, and figure that I can shoot through 2 deer with that load. Just remember the .40-200-1000 rule, it applies to pistol hunting, but just as well for muzzleloaders, as the projectile doesn't know what launched it. Use a .40 cal. or bigger bullet, weighing 200gr. or more, going 1000fps or faster, and with a properly constructed bullet you should have no problem killing deer within reasonable range(100yds or so), granted that is a general rule of thumb, and there is always exceptions, but it holds true alot of the time. Hope that helps.
~Amos
