looks to me that the marking which would be on the recoil lug was ground off. AKA scrubed All these Mausers had lives after WW2. Many of the late war rifles didn't have the bolt take down lug. they just drilled a hole in the cupped butt plate. which you have. Question is Why is the stock scrubbed and the action isn't thankfully? Some one changed the stock is my guess.