I asked Cameraland Doug about "US Made" optics a few years ago.
I could be mistaken (and will be glad to have someone correct me... seriously).
I believe the summary of the discussion was... "There is not one single lens making facility in the entire USA. 100% is made in the Pacific rim. The quality (Simmons vs. Nightforce) is specified by the company making the order and the lens are built to that specification."
Finding this fascinating, I recall I asked a few folks that worked around other lens... space telescopes... military parascopes et al. and got the same answer. Been 3-4 years and it is kinda of fuzzy, but believe I am accurate.
I find it amazing that America would deliberately kneecap herself in such a way.
I may be wrong, it happened once before, but I think most of the glass is made in Japan.