It looks to me that you have a replacement rear sight and possibly the barrel band. Can't really tell about any of the rest without better pics. If the rear sight were original the manufacturer name and serial number would be completely visable. On yours, the manufacturer looks to be covered up. Also if you look at the barrel just in front of the handguard it looks to have wear marks that indicate the presence of a type three band at one time. Some clearer pictures would help. You can also see on the stock that there is an indention caused by a type 2 or 3 barrel band. I would guess that you have a typical rebuild and possibly somebody's restoration project. That doesn't make it any better or worse than any other carbine. Still a nice example of a WW2 carbine. Enjoy it.