I just bought one of the new 270 WSM a couple weeks ago. Got it zereod in but haven't killed anything with it yet.
A friend of mine has one of the new 270 wsm's identical to it,he had it in his truck with him during deer season and it went off, shot a hole through his block. He was using factory loaded "failsafes" . If it will shoot through a truck block I would guess penetration would be pretty good on plainsgame if I were guessing. Luckily for him he was driving his old truck and not his brand new one.
We joke with him and tell him that he should of tagged it in as a 4,000 pound doe!!