[mrerick]

Hi Michal, and welcome to the forum.

The problem you describe may have occurred when a primer was pierced during firing and the high pressure gasses blew the firing pin back. This can make the firing pin guide break, or break out the back of the breech block.

The breech block is a hardened steel part that is integral to the firing mechanism. There is a fair amount of fitment needed when replacing a breech block. For that reason, you may find it more effective to have the damaged area micro-welded back, machined to correct specification and hardened.

As the breech block part may be a controlled part in the UK, it might be very difficult to import or obtain one. If the Luger is all matching, replacing the breech block would considerably drop it's value and interest to a collector in the USA.

I didn't know you could own a functional pistol in the UK. It's possible that the thing you observe was the way the gun was deactivated. Reactivating it would likely be a crime if this is the case.