Can you determine if there is a SN stamped on the rear face of the cylinder? There is something really fishy about that frame, as I think it may have been parts of two frames joined together. With the grips removed can you see any evidence of welding? I can't explain how such an earlier SN frame could have the MADE IN USA stamp otherwise. Regardless, what you have is a Frankengun, maybe an OK shooter but of no collectible value.