LGS had a couple of used Colt carbines for sale and I have questions.

They lowers were marked M4 Carbine and I want to say the SNs had LE prefixes. No "Restricted" markings on the right side. However, the uppers just had forge marks, no "C" or Cage Codes. I can't remember if the uppers had an M4 stamp near the gas tube hole. The T marks were unpainted. The barrels were govt. profile, marked 1/7 5.56 in pretty large script underneath and not C-marked. I was in a hurry so I didn't look at the BCG.

So are these all Colt or mixmasters?

The reason I ask about mixmaster is because they also had a pair of used AR-15A2 carbines with "Restricted" markings, but someone had put Rock River flattop uppers on them.  They still had Colt pencil barrels. I guess the A2s are more "practical" as they sit, but I would have preferred them with the correct Colt A2 uppers.

I guess I'm glad they didn't because I probably would have bought one.

Cop guns get worked on, rebuilt, and put back together with what is on hand depending on what is available at any given time.

I'm currently running a 20+ year old Colt "M4 Commando" F/A lower with a Geissele 10.3 patrol upper.  It's the 3rd upper to live on that lower that I know of since 2004.

If you're wanting all Colt you need to break it down and inspect before you buy.

Sounds like the complete uppers weren’t Colt.

The uppers on the M4 Carbine lowers looked like those on the "Expanse" carbines that caused so much Arfcom heartburn.

Now that I think about it, those I saw may be Expanse guns. Barrel profile sure looks right.

Good price, or not ?    The value is in the lower with the preferred markings.    I recently bought a brand new genuine Colt 6920 upper and the receiver is unmarked.   Swapping parts is not difficult, and parts with the desired markings can be traded for, bartered, or bought.    A Colt cage code marked upper is on its way to me.

Not super. $879. As I said, I was really more interested in the A2 Carbines (if they still had the correct uppers.)

Here's my$ .02 cents. Please dont quote me on the dates.... 6920 LE prefix guns, a majority of them had C roll marked or raised C marked upper receivers. Early mfg'd carbines were AF forge & Cerro forge marked with no white T marks. About 2012 or so Cerro forge marked with white T marks were the norm. All had C MP marked barrels & all had Colt mfg'd FCG. 2015 is when Colt went into bankruptcy but they still used left over inventory, C roll marked & Square Brass forge receivers then shortly after, Colt started using the Cage Code crap. The day Colt started using Cage Code parts is the day Colt started going down the shit hole. Do your research. Cage code parts were not manufactured by Colt. Cage code parts were manufactured by various Vendors to Colt's Military Specifications, ie: Mil Spec. Don't believe me do your research. 6920 carbines built in or around 2013 +/- were the last of the real Colt manufactured AR15's... When Colt started selling cage code marked carbines with dot matrix parts and Schmid FCG's those were not real Colt carbines. Those were built with Vendor parts and assembelled at Colt, then shoved inside a plastic bag and stuck inside a Colt cardboard box and called a Colt 6920. When Colt stopped using Cage Code parts, Pre CZ they used non marked parts with Cage Code barrels. On the current manufactured Colt 6920 the part Colt manufactures is the CR prefix receiver...

If I was in the market for a used 6920 I stay far away from Cop/Dept guns. Those are surplus parts, parts from parts from parts. Without completely going through a rifle yourself there's no telling what your buying cause department Armorers use whatever they have available, all their trying to do is make the gun shoot & be somewhat reliable.

Since the 6920 was mentioned above, I personally don’t think a CAGE code marked 6920 (or a factory complete rifle that is missing marks) is any better or worse than an older one that is C stamped.

The hysteria about Colt no longer being Colt because of the part markings is gunstore commando bullshit.  

Not all Colt AR's came with "C" (or "M4") marked uppers (or "13629" today) and not all LE guns have the "restricted" marked lowers so they very well could be unaltered factory built guns or they could be mixmasters? No way to know for sure unless you are the one that originally removed it from the factory box.