Off topic: But Ian from forgotten weapons just did a Slam fire vs normal fire comparison video with an 1897 Trench Gun and a tricked out 870. Was neat to watch.
Oh! On topic, I think he was doing a contest to give away the Trench gun. That's definatly what you need! :D
I watched that video a few weeks ago. It basically reinforced everything I already knew about slam firing my Dad's Ithaca 37. It's fun, but has VERY questionable utility.
Herb Parsons, the Winchester exhibition shooter, would use a Model 12 to break 7 clay birds that were thrown simultaneously. Some people accused him of slam firing the gun, so Winchester put a high speed camera on him that showed him pulling the trigger for each shot. I guess even back then people thought slam fire had more utility than it actually has.
I know where there are a half dozen completely authentic World War I Model 97 trench guns.
Unfortunately they are owned by the Pennsylvania museum system and will never see the collectors market.