Trapdoor Rifles

I have a question I need some help with. So I have looking at a lot of 1866 trapdoors on line to get better at recognition, etc. I found one that had a 1865 lockplate and another eagle mark it looked like an eagle to me. It was marked on the breech 1866 and the eagle. Also the front sight is split as if cut in the middle.

I am simply guessing that the 1865 plate was an end-of-run or a rebuild to send to France. But the second eagle is confusing me a bit. I hope it is allowable. I added the picture of it because I really can't explain where it is located. EDIT I cannot post the pic.

Location - It is opposite of the the thumb latch on the breech(?) the flat section?

It sounds as though you are talking about the eagle head which would appear with the V/P to the left of the top barrel flat:



The V and P were removed when the conversion from muzzle-loader to trapdoor was completed. Originally it would’ve looked something like this (a model 1855):

Yes that is it. Not that I am well versed but I have not seen that before. What exactly was that for? Thanks!

EDIT did more digging and they are Viewing and Proof marks. The transition to breech loader cut them away.