Adjustable sights were retrofitted to M1carbines during the later parts of WWII, starting in about 44. But with the rebuild stamp, that would be post WWII. Carbines were not being rebuilt until post war, starting sometime in 1947 if I remember right. And I believe the first rebuild station was springfield armory. And most other armories following suit in the early 50's for korea. So that means the stock at least was in the US inventory until at least Post WWII time. Which is evidenced by the cartouche.
There were repairs done in theater, but they did not stamp any cartouches in the stock. Any rebuild cartouches were done in an armory in the US after 1947.
It might be a korean war bring back, but for sure the stock didn't leave until post WWII. But that doesn't mean it still isn't a nice rifle, just not a WWII bringback.
Also a good picture of the side of the pin in the front sight would help. It's hard to tell in the pics, but it looks like it has a type I band. But if you can see any evidence of that pin being removed on the front sight, then it most likely had a type III band, that someone removed the bayonet lug. Is there a type III band shadow on the stock, or barrel? Pics of those areas will help as well. Are there any stake marks on the rear sight? All the carbines I have seen that had the rear sight changed in theater, do not have stake marks, or very light ones. If it has deep crater marks, or what I call them, those were usually put on during rebuild at an armory. More pictures of the end of the stock, and front sight will tell us more what it is.
You are right in the fact, that most early parts were upgraded during rebuild. But I've seen highwood stocks with Red River Arsenal rebuild marks, which was an arsenal rebuild station during the early parts of Vietnam. So anything could happen on the way that goes. I saw dogleg hammers in CMPcarbines. So it's anyone's guess.
But it is still a nice carbine, it is a post WWII rebuild, that is for certain. But to me that just means it has more history of serving our country. And that doesn't mean you should be any less proud of it. There aren't a lot of M1a1's floating around anymore. And many members on this site would love to have that.![]()