Alonzo thanks very much for your response and insight into the potential value of this M88 Trapdoor and sling.
I bought this Trapdoor on March 27 2004 together with a superb vet bring back M1911A1 Colt pistol rig.
I was primarily interested in the Colt rig but I took the Trapdoor because it was in the vet's son's furnace room with some rusty old shotguns.
My antique collection is focused on the U.S. Civil War period and the M88 Trapdoor does not fit within that period.
On September 26 2017 I traded the Trapdoor for a P56 East India Pattern carbine.
The Confederates bought about 10,000 of these P56 carbines during the U.S. Civil War, but the one that I have is a British carbine---with a Tower stock roundel and a VR on the lock plate.
The fellow that I traded the Trapdoor to has shown interest in a couple of my WWII guns which he would trade me for the Trapdoor plus cash.
I would not mind getting the Trapdoor back but I really had no idea what it might be worth today.
Your comments have elevated the value of what I have been hearing----but you have collected these guns and have a substantially better knowledge of them than I do.
I have no idea if there is a trade to be made--- as dealing with this fellow is like "trying to pick up Jello".
One day he is interested the next day he is not.