I'm going to be adding one of those barrels to my spring test que. Medium contour (SOCOM) barrels are an excellent compromise between weight, accuracy and heat handling. The Centurion SOCOM enhanced has some nice changes from the Colt SOCOM barrel: the mid-length gas system and the elimination of the M203 notches. And of course the Centurion gas port diameter of 0.075" works great for 14.5" mid-length gas system barrels. That's the same diameter of the gas port on the 14.5" Hodge barrel that I tested, which had zero function failures with any of the loads I fired from it.
It will be interesting to see how the accuracy of the Centurion E-SOCOM compares to the Colt SOCOM.
Colt M4A1 SOCOM Barrel Accuracy: Another Look
In 2010, I posted one of the first publicly available, in-depth accuracy evaluations of a Colt M4A1 SOCOM barrel. At that time, the Colt SOCOM barrel was relatively new to the civilian market. Many people, including myself, were pleasantly surprised by the level of accuracy/precision that I obtained with the SOCOM barrel; particularly since it is a chrome-lined, NATO chambered “military-grade” barrel. Since that time, the Colt M4A1 SOCOM barrel has developed a significant appreciation amongst AR-15 enthusiasts.
The M4A1 SOCOM barrel
Recently, I assembled another upper receiver group based on the Colt M4A1 SOCOM barrel. This new build features a Colt cage-code marked M4 upper receiver, a Colt “C” marked bolt carrier group and a 13” Geissele MK14 M-LOK free-float hand-guard.
A genuine Colt M4A1 SOCOM barrel is 14.5” long and has a medium contour; it is not an HBAR. The barrel has a 5.56mm NATO chamber and a 1:7” twist.
Colt SOCOM barrel
Colt HBAR
A genuine 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 hand-guards on the port and starboard sides of the barrel, located approximately 1.4” aft of the gas block, for the same reason. The gas port on a genuine SOCOM barrel has a diameter of 0.062” and the barrel employs a carbine-length gas system.
The SOCOM barrel has a stripped weight of 1 pound, 14 ounces. That is only 2 ounces heavier than the ubiquitous 16” government profile barrel found on the Colt 6920.
Colt SOCOM barrel
Colt 6920 barrel
The stripped weight of the SOCOM barrel is 5 ounces heavier than the stripped weight of the standard Colt 14.5” M4 barrel. The pic below shows the difference between the standard M4 barrel and the SOCOM barrel. From the gas block journal forward, the two barrels are identical
SOCOM barrel on top, standard barrel on bottom
The next pic is a close-up comparing the two barrels in the area between the chamber and the gas block journal, showing you were the extra weight is added.
The date-code on my original SOCOM barrel was “11/03” and the date-code on my newer SOCOM barrel is “02/18”
My original SOCOM barrel hand an “F-marked” front sight base. Colt no longer stamps an “F” on their front sight bases, but their newer front sight bases maintain the length of 1.98” from the top of the barrel to the shelf for the front sight post.
My original SOCOM barrel was stamped:
“C MP 5.56 NATO 1/7”
The newer SOCOM barrel is stamped with Colt’s cage code.
“13629 M P 5.56 NATO 1/7”
Both of these SOCOM barrels have the “O” stamp near the chamber portion of the barrel, indicating the barrel has a chrome-lined chamber and bore. Naturally, the M4A1 SOCOM barrel has M4 feed ramps.
Accuracy Is Final
In 2010, my original SOCOM barrel with the “11/03” date-code produced a 10-shot group fired from a distance of 100 yards that had an extreme spread of 0.90”. That group was fired from my bench-rest set-up using match-grade hand-loads and a high magnification scope.
My newer SOCOM barrel with the “02/18” date-code produced a 10-shot group fired from a distance of 100 yards that had an extreme spread of 0.93”. This group was fired off of sand-bags using match-grade hand-loads and a high magnification scope.
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