Mike,
Nice M1 Carbine.
As mentioned, if all USGI parts, you paid about half market price for it.
I particularly like the forged trigger groups.
The Inland division of GM is where they originated, and I believe that they eventually made the most. There was a second Inland plant at Saginaw Gear that made them too. My M1 came from IBM near the factory where I worked for many years in Poughkeepsie.
Rock-Ola; Underwood (my Typewriter Carbine); Winchester; Quality Hardware; Irwin-Pederson; National Postal Meter; and Standard Products were the major contractors.
The adjustable sight is a later part, with many originally shipped with "flip sights".
This website is a good one for you to study:
http://www.bavarianm1carbines.com/manufacturers.html
Marc
__________________

Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.