Am I seeing a roll pin on the front sight or is that just a shadow? I like the early spring tube with the locating tab cut off. Does your receiver also have the slide dismounting notch cut through the rail? I would not expect it for that SN. I can't really tell from the pictures. Nice carbine!
Well it has been rebuilt. The trigger housing is a type 2 National Postal Meter. The barrel band is Springfield Armory. About August 1943 for your serial number. And it looks like it's in fine shape too. Should be a good shooter for you.