Molon
8 March 2020, 06:24
Colt M4A1 SOCOM Barrel Accuracy: Another Look
https://www.ar15.com/media/mediaFiles/28568/colt_m4a1_socom_upper_receiver_group_21-1305764.jpg
In 2010, I posted one of the first publicly available, in-depth accuracy evaluations (https://www.ar15.com/forums/ar-15/-/118-486225/?) 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
https://www.ar15.com/media/mediaFiles/28568/colt_m4_socom_barrel_01_resized-1305762.jpg
https://www.ar15.com/media/mediaFiles/28568/colt_m4_socom_barrle_02_rsized-1305763.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/colt_socom_21d_resized-1305765.jpg
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
https://www.ar15.com/media/mediaFiles/28568/stripped_socom_barrel_02_resized-1305778.jpg
Colt HBAR
https://www.ar15.com/media/mediaFiles/28568/colt_16_inch_hbar_6721_02-1305761.jpg
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
https://www.ar15.com/media/mediaFiles/28568/stripped_socom_barrel_02_resized-1305778.jpg
Colt 6920 barrel
https://www.ar15.com/media/mediaFiles/28568/Colt_16_inch_government_profile_6920_bar-1305760.jpg
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
https://www.ar15.com/media/mediaFiles/28568/socom_barrel_comparison_to_standard_m4_b-1305776.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/socom_barrel_comparison_02-1305775.jpg
The date-code on my original SOCOM barrel was 11/03 and the date-code on my newer SOCOM barrel is 02/18
https://www.ar15.com/media/mediaFiles/28568/date_code_fro_socom_barrel_01-1305768.jpg
https://www.ar15.com/media/mediaFiles/28568/new_socom_barrel_date_code_01_resized-1305773.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/f_marked_front_sight_base_of_socom_barre-1305770.jpg
https://www.ar15.com/media/mediaFiles/28568/f_marked_front_sight_base_comparison_21-1305769.jpg
My original SOCOM barrel was stamped:
C MP 5.56 NATO 1/7
The newer SOCOM barrel is stamped with Colts cage code.
13629 M P 5.56 NATO 1/7
https://www.ar15.com/media/mediaFiles/28568/socom_barrel_stamp_01_resized-1305777.jpg
https://www.ar15.com/media/mediaFiles/28568/new_colt_socom_barrel_stamp_01_resized-1305772.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/0_stamp_for_socom_barrel_01-1305759.jpg
https://www.ar15.com/media/mediaFiles/28568/m4_feed_ramps_of_socom_barrel_01-1305771.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/colt_socom_barrel_10_shot_group_at_10_ya-1305767.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/colt_socom_2020_10_shot_group_at_100_yar-1305766.jpg
. . . .
As a side note, the pic below shows what a great job Ken Elmore of Specialized Armament does on his pin and weld jobs.
https://www.ar15.com/media/mediaFiles/28568/saw_pin_and_weld_job_02-1305774.jpg
.......
https://www.ar15.com/media/mediaFiles/28568/colt_m4a1_socom_upper_receiver_group_21-1305764.jpg
In 2010, I posted one of the first publicly available, in-depth accuracy evaluations (https://www.ar15.com/forums/ar-15/-/118-486225/?) 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
https://www.ar15.com/media/mediaFiles/28568/colt_m4_socom_barrel_01_resized-1305762.jpg
https://www.ar15.com/media/mediaFiles/28568/colt_m4_socom_barrle_02_rsized-1305763.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/colt_socom_21d_resized-1305765.jpg
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
https://www.ar15.com/media/mediaFiles/28568/stripped_socom_barrel_02_resized-1305778.jpg
Colt HBAR
https://www.ar15.com/media/mediaFiles/28568/colt_16_inch_hbar_6721_02-1305761.jpg
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
https://www.ar15.com/media/mediaFiles/28568/stripped_socom_barrel_02_resized-1305778.jpg
Colt 6920 barrel
https://www.ar15.com/media/mediaFiles/28568/Colt_16_inch_government_profile_6920_bar-1305760.jpg
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
https://www.ar15.com/media/mediaFiles/28568/socom_barrel_comparison_to_standard_m4_b-1305776.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/socom_barrel_comparison_02-1305775.jpg
The date-code on my original SOCOM barrel was 11/03 and the date-code on my newer SOCOM barrel is 02/18
https://www.ar15.com/media/mediaFiles/28568/date_code_fro_socom_barrel_01-1305768.jpg
https://www.ar15.com/media/mediaFiles/28568/new_socom_barrel_date_code_01_resized-1305773.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/f_marked_front_sight_base_of_socom_barre-1305770.jpg
https://www.ar15.com/media/mediaFiles/28568/f_marked_front_sight_base_comparison_21-1305769.jpg
My original SOCOM barrel was stamped:
C MP 5.56 NATO 1/7
The newer SOCOM barrel is stamped with Colts cage code.
13629 M P 5.56 NATO 1/7
https://www.ar15.com/media/mediaFiles/28568/socom_barrel_stamp_01_resized-1305777.jpg
https://www.ar15.com/media/mediaFiles/28568/new_colt_socom_barrel_stamp_01_resized-1305772.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/0_stamp_for_socom_barrel_01-1305759.jpg
https://www.ar15.com/media/mediaFiles/28568/m4_feed_ramps_of_socom_barrel_01-1305771.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/colt_socom_barrel_10_shot_group_at_10_ya-1305767.jpg
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.
https://www.ar15.com/media/mediaFiles/28568/colt_socom_2020_10_shot_group_at_100_yar-1305766.jpg
. . . .
As a side note, the pic below shows what a great job Ken Elmore of Specialized Armament does on his pin and weld jobs.
https://www.ar15.com/media/mediaFiles/28568/saw_pin_and_weld_job_02-1305774.jpg
.......