I'd suggest getting either a friend or vice involved. Have the friend or vice hold the body of the bolt, while you pad the cocking piece with a narrow strip of leather. Clamp down on the cocking piece/leather with some vice grips, pull the desired distance and rotate. On my mausers I just pull straight back, and if I don't have the stock safety, drop a nickel in the space behind the shroud to hold all in place. Then it's an easy do to unscrew the entire unit.
