Heat treating is the best way I know of to give a Mauser action a gritty feel. I got one done that was smooth as glass before heat treating, when I got it back the bolt lift and cycling had a notchy (made up word) feel. The next one I got done was also smooth before it went and the bolt would bind after it was returned.
All this can be avoided by not heat treating it. Most are fine without it. Even the 1909's.
Terry
