Stikman wrote:
> I marked this as solved because I have no idea what I'm doing.
No need to try to undo the mistake, because here is your find's very-exact ID.
It is indeed a belt buckle... specifically, a US Army sword-belt buckle, Regulation 1851 Pattern. Your specimen, like most excavated ones, is missing the stamped nickel-silver wreath which was applied to the buckle's front just below (and partially surrounding) the spread-winged eagle.
Although your buckle's wreath is missing, your photo shows there's no provision for the wreath to extend across the eagle's wingtips. Therefore, your buckle dates from sometime between 1861 and 1873. (In 1874 the buckle's design was changed and thus was known as the 1874 Pattern.
The buckle's width was enlarged in 1864, so we need to know your find's very-precise width measurement to know whether it dates from 1861-63 or 1864-73.
Your buckle shows no sign of gold-gilting, so it was made for Enlisted-men's use. (The Officer's version was gold-gilted.)
The small shallow round dimple in your solid-cast brass buckle's back means it was also die-stamped to create "crisper" detail in the emblem on its front.
The small numbers on the back are the manufacturer's "benchmark" number. Similar numbers are occasionally seen on other examples of sword-belt buckles. Unfortunately, it is definitely not an army regiment number.
UPDATE: I did some additional research for you, to narrow down your sword-belt buckle's date range. On the great majority of these 1851-Pattern buckles, the emblem either has no "rays" at all, or the "rays" are only above the eagle. Note that on your specimen, the eagle is entirely surrounded by "rays." That version was only manufactured between December 1863 and 1865.
