[Ron Wood]

My first impression was that it was a long receiver. But the link that Doubs provided confirms his observation that it is an artillery type receiver. Since the takedown bolt is in the locked position, even if the recoil spring is not engaged, the receiver should not slide forward as it shows in the picture. The receiver is prevented from moving forward out of battery by contact of the receiver lug with the stop lug on the takedown bolt. I suspect that either the takedown bolt or the receiver lug is damaged. If that were indeed true, it would seem that it would not be possible to fire this Luger, since the trigger lever/sear disconnect alignment would be wrong. A very curious gun.