colt 6933 vs cut down colt 6720

AR/M4 AR Technical Discussion
1

other than the facts that:
-I can chop the barrel on the 6720 to 12.5" (I prefer that to 11.5")
and
-the profile on the 6933 gets a little heavier forward of the FSB…

…what are the differences between these two choices?

2

…

3

It has been discussed here recently that they do not. A Colt 6720 has a regular Front Sight Base, so you need to install a taller Front Sight Post.

4

I was more concerned with port size but that’s a good difference to know…

They come with a matech so I assumed it was f hieght… Maybe someone will chime in.

5

The plan would be to cut it down, so I guess that could be rectified.

6

From what I have read it’s not F-marked but has a taller post to compensate.

Double check here: http://m4carbine.net/showthread.php?t=85670

7

Gotcha.

8

I believe the posts are the same, the one on the 6720 is just turned up a little higher to compensate for the lower fsb.

9

I don’t think it’s going to matter much in New York, since SBRs are illegal.

10

Within 2-4 weeks I should be making my second escape from NY.

This one permanent.

11

I’d buy one of these instead of modifying the Colt barrel.

https://danieldefense.com/cold-hammer-forged-barrels/12-5-inch-chf-barrels/12-5-5-56mm-lightweight-carbine-chf-barrel-w-fsb.html

I really don’t know why you want this barrel style in a 12.5" anyway. I’d rather have an 11.5" barrel.

12

I’d like to hear this as well. Ive always thought the 6933 was regarded as an optimal SBR?

13

IMHO, cut the 6720, leave the gas port at .063’‘, get VLTOR A5, get LMT Enhanced carrier, and you have an 11.5’’ carbine that will function 99% optimally suppressed, or unsuppressed with 5.56mm NATO ammo.

14

12.5" barrels were developed to use a reflex style silencer with a low pro gas block and have the shortest barrel length possible with a reflex silencer.

15

that is the eventual plan.

not to get too theoretical, but how about hanging a reflex can on a lightweight barrel - too much POI shift or not an for most?

16

I wouldn’t recommend cutting a 6720 barrel to any length. The 6520/6720 barrel is flared at the end to support the crush washer. The shoulder created during threading will not be sufficient to support the crush washer properly.

17

and that’s why M4c is what it is, thank you!!!

18

Please correct me if I am mistaken, however,

I thought it was a best practice to run a thicker barrel profile for a supressor, since you have so much dead weight out front that can cause more POI shift on the thinner profiles.

19

Correct.

20

This is also true.