Found this button back a few years ago ,its a 1 piece cast pewter .. Its a Long shot, but some of you may have seen 1 like it researching others.....Thanks
Even under super-magnification, your pewter button's front seems to be blank. The slight raised moldseam-line across its back means it was cast in a scissors-mold. So, it is apparently a simple "generic" cast pewter button, manufactured in the 1700s. Those were made primarily for use on civliam clothing, but also got used on military uniforms.