I have not shot any of the AO's, but I've handled a few.
I have one of the x series carbines #x035 sure wish i could find out more info on it any suggestions would be great This is not a Import marked gun.
The gun had that funky GI replica aluminum TH, which cracked while I was taking it down for cleaning.
There is an unusual symbol on the underside of the safe/fire selector. Moon told me some of the pains they went to in order to make the rifle 'right', some of which were evident and some things were evident that they could have went further (example, the contrasting silverish color of their extractors poor attention to detail).
Serial numbers were issued to the manufacturers in blocks. It appears to be early in Winchester's manufacture of 818,059 M-1 carbines. They were sporting rifles that looked like an M1 Carbine, but were a LONG way away from being a GI carbine. If you're interested, PM me and I'll hook you up. They were bought by Iver Johnson in 1983, who I can't say much about any collector value of an X-marked Universal, but I bet it's a good shooting gun. My buddy wants to pay off some debt by giving me his dad's Universal M1 Carbine. Cast aluminum trigger housing, stamped slide with two recoil spring, and a receiver that would no longer accept many GI parts. From 1983-1984 Universal manufactured a stainless steel carbine. USGI parts, like the Nat Ord/Fed Ord guns. They used a cast commercial receiver with nearly all GI parts. What is confusing is the serial number, the Universal web site that links to this web site says that the prefix x is for Experimental and only goes up to 400 and this one is X5$$. The serial number is X5$$ and is in front of the rear sight, Universal name and address is behind rear sight. This post will be an overview leading into a 2nd post on the Universal Firearms carbines having a serial number with an X prefix. This is the web site I have been getting most of my info from Here's an excellent history of the I doubt if any data base of serial numbers an manufacture dates exists. It means you have a 'first generation' Universal, made before the company began cheapening and redesigning internals to save money.
Setscrew, rather than pinned as the USGI is.