As far as the crack goes.... check your rear action screw to see if it still has the ferrule in place. It may be in the stock. Quite a few sporterized Mausers leave these out and it cause issues from split stocks and cracks to bolt binding due the over tightening of the rear screw. Besides acting as bedding support, the ferrule keeps the rear of the action properly spaced when tightening the rear screw.