Thanks so much Harlan! I may take you up on that. I had a situation arise here that I had to tend to and wasn't able to get the pics up. I will try again tonight. As for the compensators, yes, the military did indeed install them. They were on the arial trainers. Bruce Canfield's book, "Combat Shotguns" says"

"During the factory overhaul program requiring major repair, 8491 Winchester M12 and Remington M31 shotguns were equipped with Cutts compensators for the Army Air Force. This Cutts compensator in addition to reducing recoil in its action as a muzzle break, also permits versatility of use of each shotgun by permitting a quick change from open to full choke. In addition approximately 5,000 new M11A autoloading shotguns were procured for the Navy equipped with the Cutts compensator."

Also, here's an interesting note to keep in mind. You can indeed tell if the choke was factory installed for the military. If you have a military marked barrel with a Cutts compensator on it check for choke markings on the barrel. If there are none (like CYL or MOD) then it is factory original. If the barrel does have choke markings on it, then it was added post war (this is only the case with the Remington Model 11, to be clear). The Model 12 and Model 31 had them added during overhaul in 1944. The Model 11s did not. Hope this was helpful!