Rich I think it might be a bit later than that, 1750s or 1760s decades but just speculation. It looks like it could be a martial piece but not sure exactly where made. There is a slight crudeness to it, somewhat provincial, and I think it has a slightly archaic appearance that doesn't quite match up with when it was actually made. Where the heck is Immel when this stuff pops up?
I'd check the barrel out well and then shoot it!