This is what I did with one of mine. Not very expensive and the mount holds true.Neither, drill and tap on a dedicated turkey gun
Not an option just a suggestion that he may or may not have thought about. He may not want to drill and tap but I was just throwing it out there having been there and done that. Here is another one I used that worked like a charm on a tri star raptor. The gun had a dove tail on the receiver. I bought a dovetail mount and it worked great. I didn't drill and tap that one it worked so well. I am not familiar with the 870 to know of it has a dovetail. Again just throwing out options.Didn't see drill and tap as an option on his post , sorry ! Drill and tap for sure
I agree call William at Sumtoy and he will square you away.Drill and tap Forsure. Sumtoy makes a great mount