I found in my barn in a old tool box a part of some type. I looked at it for a while and all I could think is a breech block for a drop block rifle, maybe a sharps. But knowing its missing a few different cuts on this I established it dose not go to a sharps. But at this point I become fixated on the fact that looks like a drop block.
I propped it on a height gauge and used a 38spec. next to it for size reference.

Maybe a spencer or a hiwall browning...