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Posted: 4/2/2021 6:14:10 PM EDT
Colt 6920 Accuracy If you were given the task of designing an AR-15 barrel profile with an eye towards accuracy, handling characteristics and heat tolerance, along with a length requirement of 16 inches and a weight restriction of 1 pound 12 ounces, the odds are that the last idea that you would come up with would be the ubiquitous 16” government profile barrel with M203 cutouts that is found on the Colt 6920. (How’s that for a run-on sentence?) The profile of the 6920 barrel has more to do with accommodating an M203 grenade launcher than the attributes listed above. The Colt 16” government profile barrel has a NATO chamber, M4 feed-ramps and is chrome-lined. The barrel employs a carbine length gas system. The stripped weight of this barrel is 1 pound, 12 ounces.   These barrels are typically found with a 1:7” twist but were also produced with a 1:9” twist (AR6920DC).  The 6920 barrels that I have owned have had an “O” stamp at the chamber end of the barrel and some form of a date code stamped just proximal to the gas block journal.   The government profile barrels found on the Colt 6920 tend to show more variation in accuracy/precision from barrel to barrel than heavier profile barrels. The test results shown below were obtained with free-floated barrels. One Colt 6920 barrel tested from my bench-rest set-up at a distance of 100 yards using match-grade hand-loads produced three 10-shot groups fired in a row that had extreme spreads of: 1.42” 1.19” 1.56” for a 10-shot group average extreme spread of 1.39”. The mean radius for the 30-shot composite group was 0.44”. The smallest 10-shot group . . .  The 30-shot composite group . . .  Another Colt 6920 barrel tested under the same conditions as described above produced three 10-shot groups fired in a row that had extreme spreads of: 1.59” 1.55” 1.73” for a 10-shot group average extreme spread of 1.62”. The mean radius of the 30-shot composite group was 0.54”.  … |
I enjoyed the info.
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Quoted: Ammo used in the test? Something better than LC M193? Sierra's 55 grain Blitz Kings..... is his usual fodder of choice. 52/53 grain match bullets from all the major makers can be tuned to shoot great from almost any barrel. The greatest accuracy handicap any rifle faces is military surplus FMJ's. |
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Quoted: Yes. https://www.ar15.com/media/mediaFiles/28568/55_blitzking_vs_55_fnj_003-1893921.jpg This is what hand-loaded 55 grain BlitzKings can do from one of my Krieger barreled AR-15s. https://www.ar15.com/media/mediaFiles/28568/sierra_55_blitzking_10_shot_group_21b_ti-1893922.jpg .... Thank you, sir! |
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