Unbagging a Colt M4A1 SOCOM barrel.


Shawn did an interesting accuracy test on a Colt 14.5 inch M4A1 SOCOM barreled upper of mine a little while ago.  His results can be read here.

Here is what a Colt M4A1 SOCOM barrel looks like new in the bag:

Colt M4A1 SOCOM barrel


Note the cardboard wick in the barrel.

Colt M4A1 SOCOM barrel


Colt M4A1 SOCOM barrelBarrel markings and F Front Sight Base (FSB) are clearly marked.

Colt M4A1 SOCOM barrel


This picture shows the yellow dot of paint found on new Colt barrels.  Also note the flats in the heavy barrel profile and notches in the handguard cap required for mounting a M203 grenade launcher.

Colt M4A1 SOCOM barrel


Colt AR15 barrels usually have a date stamp near the hand guard cap, this one is 06/11.

Colt M4A1 SOCOM barrel


The wick in the barrel extends past the chamber.

Colt M4A1 SOCOM barrel


While a new in package M4A1 SOCOM barrel comes with a complete FSB (front sight post included), no muzzle device or slip ring/delta ring are included.

Colt M4A1 SOCOM barrels can be found for sale from various sources.  These all are 14.5 inch barrels so it will need a permanently attached muzzle device to be legal on a non-NFA firearm.  The Colt 6920 SOCOM model comes with a similar barrel that is 16 inches in length and does not have the M203 flats milled into it.



    • No. You register a firearm as a SBR. That firearm will then need to be engraved by the manufacturer(person/trust/corp) that made it a SBR. That engraving can be on the receiver or barrel.

  1. The “wick” is a VCI (volatile corrosion inhibitor) rod, standard for military rifles and barrels that are packed for storage or shipment.

    Easier to clean up than a bore full of cosmoline, and no chance of plugging up the gas tube with grease.

  2. Are you sure the LE6920 SOCOMs don’t come with the M203 flats milled into them? I’m talking with a guy selling one in an auction & claims that several years, before Colt went to shit they sold them this way.

    • The barrels I have personally seen did not have the M203 flats.
      That said, I certainly haven’t seen all the barrels out there.

      • Okay thanks. I was just wondering if that was more of a military only build or not. Seems like it, but I’m seeing an auction for one that has them. Just makes me wonder.

    • Colt sells SOCOM profile barrels with and without the M203 cuts. some came without for a while because not many people wanted or knew about it anyway. COlt quality has certainly not “went to shit” regardless of flats on the barrels. I have a 6940P from 2015 with the SOCOM barrel with M203 flats

      • Is there really any advantage to having them other than bragging rights? Or truly mounting a M203 launcher to it. I mean, I like Colt. I guess when I said that, I meant that they switched from the Knights to Troy Rails and stopped milling making those cuts. Also dropped the top handles. I’m not an expert on guns. I just picked up a Socom without the cuts and I’m wondering if it was worth it, or if I should try getting one with them.

  3. My understanding is that the Socom barrels are button rifled and not cold hammer forged. They are reputed to have greater accuracy over the standard M4 barrel.

    The additional barrel weight was added to mitigate the effect of barrel heating on full auto fire and hopefully eliminate damage to the heat treat of the barrel from extreme full auto fire.

    • Colt M4 profile barrels are made the same way as the SOCOM barrels and are very accurate themselves wen used with match ammo buy some one who tries. No colt barrel is outside of canada is hammer forged and the Colt Canada barrels are not used in the US


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