Hello from Kingston. If you can't find any, I suggest Challenger slugs. Imagine a 547 gr. rifled slug at 1610 fps. I have used about 4 boxes in the last 5 yrs. and they will stop (dead in its' tracks) up to bear, moose and anything in its' size and weight. Also try some more feedback from CGNers. Good luck, Smokey123.
p.s. If you buy some, better also buy a shoulder pad (ouch!)