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Molon
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Posted: 2/28/2010 8:43:07 PM
[Last Edit: 8/5/2010 3:28:36 PM by Molon]
The Colt M4A1 SOCOM Barrel





A genuine Colt M4 SOCOM barrel is 14.5” long and has a medium contour underneath the handguards (not a heavy barrel profile). The barrel has a NATO chamber and a 1:7” twist. The SOCOM barrel has the typical M4 circumferential cut-out located approximately 1.4” forward of the gas block for the attachment of an M203, as well as rectangular shaped cut-outs underneath the handguards on the port and starboard sides of the barrel, located approximately 1.4” aft of the gas block, for the same reason. The SOCOM barrel employs the carbine length gas system.











The barrel stamp located just aft of the flash suppressor reads:

C MP
5.56 NATO 1/7








The barrel has an “F” marked front sight base and a side sling swivel. The “F” mark is located on the port side of the front sight base.











The SOCOM barrel will have a “date code” located immediately aft of the handguard retaining ring. The handguard retaining ring itself will also have cut-outs located at 4:30 and 8:30; again for the attachment of an M203.








The barrel will also have a small “O” stamp, that is located at the chamber section of the barrel, indicating a chrome-lined chamber and bore.







Naturally, the SOCOM barrel will have M4 feedramps and there will be a numeral “4” stamped at the 3 o’clock position on the barrel extension.







Here are a couple pics comparing the SOCOM barrel to the standard M4 barrel.










Accuracy Evaluation



I performed an accuracy (technically precision) evaluation of the Colt SOCOM barrel following my usual protocols. All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) For the accuracy evaluation, the barrel was free-floated using a Daniel Defense Omega rail.




This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any Group Reduction Techniques (e.g. fliers, target movement, Butterfly Shots).

As many of the significant variables as was practicable were controlled for. The free-float handguard of the carbine rested in a Sinclair Windage Benchrest, while the stock of the carbine rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.





The Wind Probe.





Using match-grade hand-loads topped with Sierra 55 grain BlitzKings, I fired three 10-shot groups from the Colt SOCOM barrel in a slow, steady manner from 100 yards. Those groups had extreme spreads of:

0.90”
1.02”
0.93”

for a 10-shot group average extreme spread of 0.95”. All three of the 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the composite group was 0.35”.

The smallest 10-shot group.





The 30-shot composite group.






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badazzar15
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Posted: 2/28/2010 9:19:24 PM
Nice write up Molon.
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Posted: 2/28/2010 9:25:31 PM
Great work, Molon.

I assume GI barrel assemblies will include A2-style flash hiders; is this correct? What model are the flash hiders on the barrels in your pictures? Are they the same model? The SOCOM's FH seems to have straight tines, while the M4's tines go counterclockwise.
"--you can't conquer a free man; the most you can do is kill him."
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Molon
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Posted: 2/28/2010 9:51:56 PM
Originally Posted By GHPorter:
Great work, Molon.

I assume GI barrel assemblies will include A2-style flash hiders; is this correct? What model are the flash hiders on the barrels in your pictures? Are they the same model? The SOCOM's FH seems to have straight tines, while the M4's tines go counterclockwise.


You're correct. My two barrels have permanently attached Vortex flash hiders to bring them to the legal length. No SBRs allowed for the unwashed masses in my state.

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badazzar15
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Posted: 2/28/2010 9:55:02 PM
Originally Posted By Molon:
Originally Posted By GHPorter:
Great work, Molon.

I assume GI barrel assemblies will include A2-style flash hiders; is this correct? What model are the flash hiders on the barrels in your pictures? Are they the same model? The SOCOM's FH seems to have straight tines, while the M4's tines go counterclockwise.


You're correct. My two barrels have permanently attached Vortex flash hiders to bring them to the legal length. No SBRs allowed for the unwashed masses in my state.



One of those Vortex's is a Dan Young and the other is a Smith Enterprise?
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fax: 866-283-2215
Molon
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Posted: 2/28/2010 9:55:36 PM
Originally Posted By badazzar15:
Originally Posted By Molon:
Originally Posted By GHPorter:
Great work, Molon.

I assume GI barrel assemblies will include A2-style flash hiders; is this correct? What model are the flash hiders on the barrels in your pictures? Are they the same model? The SOCOM's FH seems to have straight tines, while the M4's tines go counterclockwise.


You're correct. My two barrels have permanently attached Vortex flash hiders to bring them to the legal length. No SBRs allowed for the unwashed masses in my state.



One of those Vortex's is a Dan Young and the other is a Smith Enterprise?


Bingo!

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TAT2
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Posted: 2/28/2010 11:35:48 PM
Molon,

Just curious, where dd you get the upper and who welded the Vortex?

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vugger
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Posted: 2/28/2010 11:57:48 PM
Ummm...Am I the only one who cannot see any pics?
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brazos609
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Posted: 2/28/2010 11:59:26 PM
People looking to buy a SOCOM barrel need to be alert to the length. There were alot of them sold last year that the factory threads had been cut off, shortening the barrel 5/8" to 3/4", and then new threads cut. They had the step directly behind the threads recut but maybe some didn't. They were reparked and often sold as new or new take-offs. They may shoot fine but there is no reason to pay a premium for a cut down mis-represented barrel.
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Posted: 3/1/2010 9:28:07 AM
Stripped down, they look like this:



buddyhoohaw
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Posted: 3/1/2010 9:37:15 AM
Excellent illustrative write-up Molon! Of course, I already knew it all.

Cheers
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Molon
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Posted: 3/1/2010 10:10:20 AM


Would you mind weighing the stripped barrel and posting your results?

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98Z5V
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Posted: 3/1/2010 1:57:30 PM
Originally Posted By Molon:


Would you mind weighing the stripped barrel and posting your results?



My apologies, Molon - that barrel was only in that state for about a week, and I didn't get a weight on it. It's completely built now, with a pinned Phantom on it. Sorry, man...
faldoc
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Posted: 3/1/2010 4:47:32 PM
Thanks for the write-up.
My Socom barrel has the exact same markings, made in 04/04.
The gun on the left is the one with that barrel. Colt M16A1, DD Omega, Magpul parts. I have replaced the FCG with Geissele parts, and it has an MGI buffer with Wolff extra power recoil spring.
plinkr415
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Posted: 3/1/2010 4:54:21 PM
Who's receiving the M4's with SOCOM barrels?
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1saxman
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Posted: 3/1/2010 5:09:26 PM
Thanks for posting this article, and great work on the pictures. I got tired of looking at all that barrel sticking out on my Colt 6721 so I sent it to ADCO for a chop job - from 17.5" (w/FH) to 16.10" w/FH pinned. At the same time I have a middie/med-con upper being made at CMMG for another carbine. Having the Colt HBAR now with a more 'correct' barrel length, I doubt if I will build another carbine, but the SOCOM barrel sure looks good. I guess the 'medium-contour' CMMG barels are about the closest to it, at least under the guards - except for the mounting cuts, of course.
Oniak
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Posted: 3/1/2010 5:16:29 PM
Originally Posted By badazzar15:
Originally Posted By Molon:
Originally Posted By GHPorter:
Great work, Molon.

I assume GI barrel assemblies will include A2-style flash hiders; is this correct? What model are the flash hiders on the barrels in your pictures? Are they the same model? The SOCOM's FH seems to have straight tines, while the M4's tines go counterclockwise.


You're correct. My two barrels have permanently attached Vortex flash hiders to bring them to the legal length. No SBRs allowed for the unwashed masses in my state.



One of those Vortex's is a Dan Young and the other is a Smith Enterprise?


I've never seen that Young flash hider. How does it compare to the Smith Vortex? Sorry to go off topic.
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vugger
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Posted: 3/1/2010 8:00:07 PM
I am a big SOCOM fan and would love to see these pics, but I am getting nothing. I am not even getting any red X's . Molon, did you remove the pics from the writeup?

Thanks!
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sterinn
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Posted: 3/1/2010 8:22:57 PM
My M4 Match Target has all of that except for the Medium Profiled barrel.-
Steve
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Molon
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Posted: 3/1/2010 8:46:36 PM
[Last Edit: 3/1/2010 8:46:59 PM by Molon]
Originally Posted By vugger:
I am a big SOCOM fan and would love to see these pics, but I am getting nothing. I am not even getting any red X's . Molon, did you remove the pics from the writeup?

Thanks!


They're all showing up on my screen. Try hitting your refresh button.

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seannw1
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Posted: 3/1/2010 8:56:58 PM
I'm seeing the pictures with no problems.
vugger
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Posted: 3/1/2010 9:32:41 PM
[Last Edit: 3/1/2010 9:34:27 PM by vugger]
This is VERY weird. I cannot get them to show up no matter what I do. It's like they were never even posted, just text. ??

ETA: I can see everyone's pics except Molon's. Never had this happen before.
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Combat_Diver
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Posted: 3/2/2010 1:04:10 AM
The FH isn't a straight A2 model. There is a notch (@6 o'clock if I remember correctly) for mounting the issued suppressor. Special Forces Groups are issued the SOCOM barrels but only at ODA level. HHC's and Group Support Battalion have the standard M4A1.

CD
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Posted: 3/2/2010 3:16:15 AM
A far as I know Colt and CMMG both stopped making this barrel. I think Socom stopped asking for it and decided to use a standard M4 barrel to save weight.
GHPorter
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Posted: 3/2/2010 7:50:58 AM
Originally Posted By vugger:
This is VERY weird. I cannot get them to show up no matter what I do. It's like they were never even posted, just text. ??

ETA: I can see everyone's pics except Molon's. Never had this happen before.


Do you see other people's Photobucket pictures? Could your ISP be blocking Photobucket?
"--you can't conquer a free man; the most you can do is kill him."
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vugger
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Posted: 3/2/2010 8:07:41 AM
Originally Posted By GHPorter:
Originally Posted By vugger:
This is VERY weird. I cannot get them to show up no matter what I do. It's like they were never even posted, just text. ??

ETA: I can see everyone's pics except Molon's. Never had this happen before.


Do you see other people's Photobucket pictures? Could your ISP be blocking Photobucket?


I see everyone else's pictures, just not Molon's.
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