The USA was probably an importers's mark,unless it was in the usual place for Made in the USA. (Forward lower right part of the frame.)
Be advised that some .38/200's have been re-chambered for .38 Special and sold here. Do NOT buy one. (Bad investment, questionable safety.)
If the barrel is five inches long, not four, you probably saw one of those .38/200's made for the British Commonwealth nations. Some of those were with four-inch barrels, but a true US Victory Model will have a four-incher or the rare two-inch barrel. If this barrel was actually six inches, you certainly have a Commonwealth model. They came with four, five, and six-inch barrels. all five- inch after April, 1942. Priot to then, they were blued. Later ones had a Midnight Black finish, and some were refinished that way or Parkerized.
Pachmayr is spelled like that, not the way you did it. I'd sure check under the grips before buying ANY handgun. Rust sometimes occurs there, as people don't take off the grips and oil under them.
IF this gun is still in .38 S&W regular, NOT .38 Special, it is a legitimate British collectible. Go to the British Gun Pub at
www.gunboards.com and post about it there for current values. Personally, I wouldn't give over $250, if that, and only if it was arsenal refinished and the work was really well done. It was originally commercial quality blue, IF you are correct about the six-inch bbl.
T-Star