I use quite a few calibers over the course of a season . I also hunt two different states , using everything from 223 , 22-250 up to 300 RUM and a few 44 mags and a 45-70 thrown in . I'm going to say 30-06 165 Gr Ballistic Tip , Like anything else shot placement is key but that load in the boiler room is either DRT or a blood trail Ray Charles could follow.