Gun part found metal detecting

I was metal detecting and uncovered what looks like silver plated brass. The rings are not the same size. One side is 0.722" and the other is 0.694". One side is flat and there are marks on the inside that look to be from where the rings were brazed together. There are no marks, or stamps of any kind that indicate any information. Other than knocking the dirt off, the way it's pictured is the way it came out of the ground. Between my neighbor and myself, we guess it's from a shotgun or musical instrument. If its a shotgun part, I'm hoping someone can point me to the model this could have come off of. It's a longshot but the firearm community if full of knowledge. Feel free to make another guess. Thanks for any ideas.

I believe this is a cut off from the front end of a 12 gauge double-barrel.

Interesting. Still along the lines of originating from a shotgun.

Looks more like part of a brass instrument to me. I believe the flats are for getting a better soldered joint with the instrument. That gray schmoo might be solder?