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12/6/2019 7:27:02 PM
Posted: 1/20/2008 1:21:16 PM EST
Is there any real difference between (for example) a Colt 6920 barrel and a Colt 6721 (heavier) barrel? Obviously the heavier straight barrel will weight more. Anything else of signifigance? Otherwise the 6920 and the 6721 are the same weapon?


Link Posted: 1/20/2008 1:26:39 PM EST
I believe the 6721 is a 1/9 twist barrel, and the 6920 is a 1/7 twist barrel.
Link Posted: 1/20/2008 2:33:03 PM EST

Originally Posted By Freakinout:
I believe the 6721 is a 1/9 twist barrel, and the 6920 is a 1/7 twist barrel.

I can never keep track of Colt model numbers so I could be wrong, but as a general rule Colt's barrels with military profiles have 1/7 barrels with a chrome lined barrel and chamber while the heavier profiles have a 1/9 twist with a chome chamber but not a chrome bore. Confirm that info before you make any decisions, but that should give you an idea of what to look at.
Link Posted: 1/20/2008 2:41:01 PM EST
The 6721 is HBAR with 1/9 twist. The 6920 is gov't profile with 1/7 twist. Both are 16", F marked FSB, and both have M4 ramps..
Link Posted: 1/20/2008 2:46:24 PM EST
[Last Edit: 1/20/2008 2:49:37 PM EST by MMcfpd]
So a 6721 barrel does not have a chrome lined bore?

ETA - I just looked at mine; damned if I can tell, but it is shiny.
Link Posted: 1/20/2008 2:52:10 PM EST
6721 has a chrome lined chamber and barrel
Link Posted: 1/20/2008 5:03:18 PM EST
+1. All my 6721 barrels are fully chrome lined.
Link Posted: 1/20/2008 5:44:54 PM EST
With the twist being so close, I would imagine for general plinking/target shooting out to 200 yards I will not see much of a difference in performance in the two barrels with the same weight bullet. The difference might occur between heavier grain and lighter grain bullets though? But even at that range, wouldn't the difference be nominal?

Link Posted: 1/21/2008 7:08:47 PM EST

Originally Posted By George_in_Wis:
+1. All my 6721 barrels are fully chrome lined.

Mine also....
Link Posted: 1/22/2008 2:08:31 AM EST
Just weight and twist. Both the 6721 and 6920 are fclb&c.

6721 Hvy barrel 1/9
6920 M4 profile 1/7

6721 is a little front hvy in the hands.
Link Posted: 1/22/2008 2:18:55 AM EST
On Colt's site the 6721 is listed as being a little over a full pound heavier than the 6920.
Link Posted: 1/22/2008 12:08:25 PM EST
Got near perfect balance with my 6721LE by switching to an A2 butt with the
corresponding receiver extension, buffer, etc. Also added M4 wide oval
handies, and a Magpul MIAD grip. Just got rid of the gigantic carry handle
knobs with poly lock 10-32 nuts.....and this massive carbine is rapidly
becoming my favorite EBR ! That outrageous tube is like having a SOCOM
on steroids !
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