You may be right, I have whats called a “trench gun” or riot shotgun, its a 1933 Winchester Model 11, looks just like a Browning humpbacked A5 auto 12. Has a cut down barrel and stock.
>> I have whats called a “trench gun” or riot shotgun,
Does it have a bayonet lug? To my mind, it is not a trench gun if not.
See here:
http://www.olive-drab.com/od_other_firearms_shotgun_m12.php
The sentry in the first pic has a riot gun. Scroll down a little, and there’s a trench gun with a bayonet lug.
Also, I presume it’s a Winchester Model 12?