I did a quick side-by-side and was wondering, besides the lack of a bayonet lug on the MT, what are the differences?
Thanks,
Chris
If I remember correctly the MT6400C has a fixed buttstock and a muzzle brake instead of flash suppressor to comply with ban requirements. The rollmarks, of course are different as well.
Looking at the pictures from the Colt web sights, it would appear the muzzles devices are different. I wonder what differences there are in components, if any. Ultimately, I’m trying to decide which one to order.
6920
MT6400C
Right now it really depends on what you can find. If you are offered both and at the same price, go with the 9620. You may be able to find a better deal on the 6400 though and if you’re going to change out the stock and/or muzzle device anyway you might as well go with the cheaper model.
The 6400c comes with the cut down, neutered style bolt carrier whereas the 6920 will come with an M16 carrier.
Interesting, I wasn’t aware of that.
6400C also comes with 9 round magazines. Other than that, I think the other posters have covered the main differences.
Good info, thanks!
get the 6920
The 6400 will have a stock that will not adjust. It would have to be completely replaced (approx $80 - $175), depending on the mfg.
The 6400 will have that silly muzzle devise. To replace would cost $50-$100
The 6400 will not have a regular size mag (value $15)
The 6400 will not have the M16 carrier.
The 6400 will have lower resale value.
If the features listed above don’t mean much for your use, than the 6400 is a high quality option.
I have owned both models. My understanding is the last batch of MT6400s came with a M16 bolt carrier. The switchover was Colt wide, older 6920s didn’t have the M16 carriers, IIRC. I didn’t think Colt made the Match Target series any more, are they still producing 6400s?
The difference is the rollmarks, pinned muzzle brake versus threaded on flashhider, fixed faux collapsible stock versus real collapsible, bayonet lug missing on the 6400.
I’d get the 6920 unless you are legally bound to get 6400, or it costs enough less that de-bannifying it would be less than getting a 6920. They do have “M4 Carbine” rollmarks, which are kind of cool, but I didn’t like the “Match Target”.
I bought a 6400C back during the stupid AW ban and that thing still runs like a Singer sewing machine!! It is truly a fine “almost-true Colt” M4 for those that think Colt is G-D. Mine came with that ridiculous muzzle brake too. In my opinion, that is the number one reason not to get one now that you have the choice between it and a 6920.
That said, I had the brake removed, a phantom put in its place and added a Magpul CTR and I will never get rid of that rifle. If I could have a bought a 6920 for just a couple $100 more back then I would’ve though.
Does the 6400 come 1/9 barrel and the 6920 come with a 1/7?
Nope. My 6400MT has a 1:7" twist.
I have a 6400c and I replaced the buttstock with an OEM Colt M4 4-Position Buttstock, Replaced the Barrel with a Colt LE6921 14.5" w/ Pinned Elongated A2 FH, Replaced the Trigger Springs with JP springs and It never Hiccups ! Not once. The “M4 Carbine” Roll Marks are cool too…Damn Fine M4 ! 
A big plus one to that. The last I heard, the MT line was killed off in early 2005.
Looks like this has worked itself out since the MT line has been discontinued.
Maybe a Collectable in the future, Since it’s not made anymore…
Let’s hope. 
Good point - could removing the crappy brake diminish the value of the rifle since it’s not in its original configuration. . . . not that it’s being sold in my lifetime but it’d be nice to know.
-Boris
Since I swapped Barrels , And Buttstock , I still Have the Stock Parts. But I would never sell it anyway…:rolleyes: