I always told my hunting partner that mechanicals werent the way to go in the elk woods. he disagreed and has been running 125 grain schwackers (Montana). Hes shooting an 80 lb omen pro at 29 inches. flinging a 460 grain arrow at 330 fps (or really close) Anyways on saturday he shot a spike elk in the shoulder at 30 yards that I called in. Found his arrow and he got 3"s of penetration. The head broke off inside the insert, arrow was undamaged. I know the shot wasnt ideal, but I feel if he had been shooting a fixed steel head it would of crushed through the shoulder and gotten plenty of penetration to kill the elk quickly. Hard to say, but I wont ever be running mechanicals any time soon. Never had a problem getting fixed heads to shoot the same as my fp's so that argument doesnt hold up for me. You may get a larger cut, but if you cant get the penetration I dont see the point.
Never did find the elk and im still a bit heart broken over it.