M1 Carbine Question

I have a M1 Carbine that has a UN-QUALITY receiver (#4432782) with a Inland/GM barrel dated 6-44. It also has a flat top carrier bolt. Questions: 1) It has a serial number that does not appear in the serial number list I saw on this forum. 2) It has a metal handguard which looks original but I think it is not, did they have it? 3) If it should be wood, should it be a two rivet or four rivet? 4) Where can I find a correct rear site? This one has a screw mount adapter for a scope (which I assume is after-market) and it has a muzzle flash shield on it too. Just looking for answers to get to stock original configuration.

Edited by W5USMC - Mar 25 2023 at 11:30pm

Thank you, I will get a few more pictures tomorrow. From what I read the barrel is most likely the original. It is an Inland Mfg. Div. General Motors 6-44. Also from what I understand it was one of the airdrop carbines to the French in late 1944. I did assume the ventilated handguard was something added, however it does appear to be period correct and from what I understand mostly used on paratrooper carbines but I was told some regular ones did have them. However, they appear to be ones later in production. Also, with the flat top bolt it certainly must be one of the last ones since in mid 1944 they used the round tops. 

Thank you for the information. Much appreciated.

I did find rebuild markings on the carbine. It has an MR (Mount Rainier Ordinance Depot, Fort Lewis, WA) stamped on the left side just in front of the sling cutout. Also in the cutout are the markings LA for Inland as the prime contractor and S.E. Overton South Haven, MI as the manufacture. Also noted that as seen in a prior post the receiver has a comma as shown "U.S. carbine cal. .30,M1". Other people have stated that is not normal but this one also has it quite clearly. Sorry, I cannot figure out how to post pictures again. I have more but don't know how to insert them. 

That's it, I wasn't signed in, thank you. I thought since I could see everything I was automatically logged in when I go to the page through link in my email. Thank you. The sling is obviously a after market or post war, the stock appears to have been sanded, I think the stock is birch which apparently they were using in 1943 and on. Also, is there a significance to the magazine release having an "M" stamped on it?