Please see the thread referenced below:

www.uzitalk.com/forums/showthread.php?s=&threadid=5386

Thanks.

I never seen that before like that, sure is ugly as hell.  My guess was gonna be same as the poster.

Possibly a thread protector if the weapon was fitted with a suppressor.
WWII suppressors were not like the modern equivalents that could take thousands
of rounds, and as such were removed/replaced as needed.
They used similar size cylinders to retain weight and profile configuration
when the suppressor was not in use.

Or maybe it's a shotout can? [shrug]

Or maybe someone gutted a shotout can?

I have see a pic of that in a old book about the OSS-Office of Strategic Services. It's a suppressor. It used "wipes" instead of machined baffles like today....it would loose it's suppression ability at about 75-100 rounds. Because that one had a full barrel it could have been a demostration gun....

The OSS and the British SOE would use them in single shot mode as sentry elimination tools. They were never air dropped to the French or anyone else. There were only a handful of examples made and I had thought that the book said that none had survived the war.....

They discontinued the use of them in favor of a supprressed pistol.......

If I can track that book down I will post that pic....

I`ll vote its a supressor.