The sock says manufactured in US and I assume USFA used US parts. They are supposed to be quality pieces from what I have heard.
bearcat6 - what does your Nettleton say on the barrel? Should have a US address stamping?
I'm not an expert but I have a USFA Custer Battlefield model that is about 100 serial numbers higher than this Ainsworth. The Custer's were part of the Inspector Series and as best I can tell they started making them in 2005. I believe all Custer's were 100% American made as that is well after USFA went to all American parts. The Custer is basically an Ainsworth but with a faux antique finish rather than bone case and oven blue.
I do think this Ainsworth is 100% American made. The standard American made USFA Single Actions did have a fat front sight and wide notch rear sight but the American made Ainsworth's had a thin front sight and small V-notch rear. The ejector rod housing on this Ainsworth is American style. If you look close you can see that the front part of the slot has a gradual angle. The Italian ejector housing slots had a sharp angle. The flutes also are American style because they are wide with round ends that stop at or before the cylinder notches. The Italian style flutes were narrower, more pointed and they extended past the cylinder notches.