Hey all!

 Just purchased a complete MT6601c upper off the EE and I have some questions...
First is it did not have the pinned comp on it, anywhere I could find one?

Second is it has an old looking aluminum round free float tube on it. Was this a factory option? If not anyone know it’s origins? And can I return it to the stock a2 handgaurds with delta ring and triangle end plate? Here’s some pics... thanks in advance fellers.

I have plans to put this on a PSA m16a2 rollmark lower I just purchased or maybe flop it over to my m16a2 clone lower. We shall see..

The upper


FSP end


Barrel markings


Receiver end


BCG


THIS is not the actual rifle but a pic for reference what the comp looks like from factory..


Thanks again!

Also thinking about a smith threading it for an a2 comp...

If there’re no sign of the pin/pins that held the Comp in place then it’s not a MT6601C but a standard MT6601.

The FF tube was not an option.
The 6601 and 6700 both came from the factory with the standard A2 handguards.
Only the Colt Accurized Rifle with the SS barrel had a FF tube and chopped FSB.
Once you find a way to remove it you can install the original parts back.
I’m not familiar with that kind of HG but using a strap wrench you should be able to remove it.

ETA
I own a MT6601 as well.. I had the barrel threaded for a A2 FH.
Have the same C AF markings on the receiver.. I guess your was made in the same time frame as mine.. April 2000. You’ll find the barrel mfg date under the HGs near the FSB.

Wow thank you! The cutouts are there for the pins... but no comp. so I’m definitely going to have it threaded. What kind of accuracy do you see out of yours?

Mine is a good shooter.. only the chamber is chromed, the bore is not.
I’ve converted it into a SPR style rifle and with Hornady 75gr I get 1moa easily.. sub moa in the good days.

ETA
The 6601C was not available in 2000 when I got mine.
I’m sure in 2008 it was already available because I still have a brochure somewhere.. but I think it was introduced in 2004 but I could be wrong.

Wow thank you again, can’t wait to try mine out! Now these are marked .223 on lowers , since they are “match target” rifles, are the chambers not 5.56 NATO? Can I shoot 5.56 out of her?

No problem the barrel is marked 556.

The 223 on the lower made it easier for colt to sell it in countries where military calibers are restricted.

I have a Colt Firearms Buyer's Guide from 1999, and it shows the MT6700C, buts lists it and the 6601C.  So, maybe it was available then here in the States.
I also have the barrel from a 6601C that I bought off of eBay or Gunbroker about 15 years ago.  There were two compensators used on these rifles.  Mine has the compensator like in the book, but different from the one you show.  It's longer and has slots only on the top.  I think that the one in the photo you posted was used later in the run.

Great info man thank you! I’m having the hardest time finding a comp for this. Glad there’s two types... I kind of want to keep it with pinned comp but if I can’t find one I’m going to definitely thread her.

Nice score!

I’ve found online the 1999 colt catalog and you’re correct.
I was also reading the BlackRifle2 today and Bartocci mentions also the MT6601T but I can’t find more info online.