I have a 300 WSM built on a long action. Looking for loads for 212-215 gr bullets. Can set seat out to COAL of 3.3"

try longrangehunting.com

Never had much success myself with bullets that heavy in with short mag, WSM or SAUM... Why don't you just load some TSX's in 180 grain over a stiff charge of H-4350, that bullet will penetrate equally or better than those heavy bullets in my opinion.