but they stopped in April 1944, so the barrel would have to have gone from Underwood to NPM almost as soon as it was done. The last batches of NPM are often seen with IBM undated barrels. You have to look for the P with a small prick proof nearby to identify an NPM mounted barrel. I'd certainly consider keeping that carbine as NPM are very high quality and you have all the elements for a good shooting weapon there.