That's what I think too. The real ones are solid and flat on the back, at least the ones that I've seen. I pulled up several 1851 officer buckles on the internet and they all have some variances. But they are all solid on the back. What do you know about it? Did you dig it up? Where? How deep?
Yeah I dug it, it was a few inches down at an old old park. Thats what I thought about the back. this is stamped looking, fairly solid though. Maybe an early re-enactment piece .
What I would recommend is that you post it on the Real or Fake forum. There are some pretty smart folks over there. I bet they could clear it up for you in a hurry. Good luck. My fingers are crossed for you.
Yes, that is the same plate. I will try to find another example, but that is your plate.
And in terms of the authenticity, of course it's real. And it is a great find. No reenactor would be using a post-CW plate. And they are not worth a massive amount, so it would be too much trouble to counterfeit them. Congratulations on a really nice keeper!