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Posted: 7/6/2010 2:02:00 PM EDT
Winchester Q3131A1
The velocity specification for M193 laid out in MIL-C-9963D calls for an instrumental velocity of 3250 fps, plus or minus 40 fps, at 15 feet from the muzzle, with one standard deviation not to exceed 40 fps. This is from a 20” test barrel that does not have a gas system. The M16/AR-15 loses approximately 20 fps due to its direct impingement gas operating system, which gives you a velocity range of approximately 3190 fps to 3270 fps at a distance of 15 feet when fired from a 20” barreled M16/AR-15 or a muzzle velocity of approximately 3210 fps to 3290 fps depending upon the exact B.C. The lot of Winchester Q3131A1 that I chronographed was fired from a 20” Colt barrel with a NATO chamber, chrome lining and a 1:7” twist. It had a muzzle velocity of 3180 fps with a standard deviation of 24 fps for a 10-shot string. Temperature: 78 degrees F Humidity: 31% Barometric pressure: 30.08 inHg Elevation: 950 feet above sea level The U.S. mil-spec accuracy requirement for M193 calls for 10-shot groups of the ammunition to be fired from a machine rested, bolt-actioned test barrel. The mil-spec testing is conducted from a distance of 200 yards and the dispersion of the shot-groups is measured using the mean radius. The accuracy spec requires that the average of the mean radii of all the 10-shot groups is not to exceed 2 inches. A mean radius of two inches at 200 yards equates to an extreme spread of approximately 6 inches or approximately 3 minutes of angle. I performed an accuracy evaluation of the Winchester Q313A1 load following my usual protocol. Shooting was conducted from a concrete bench from a distance of 100 yards (confirmed with a laser range finder.) The test vehicle was a 16” Colt HBAR with chrome-lining, a NATO chamber and a 1:9” twist. This is the barrel found on the Colt 6721 Tactical Carbine. The barrel was free-floated with a LaRue Tactical handguard. 
The fore-end of the carbine rested in a Sinclair Windage Benchrest and the butt-stock rode in a Protektor rear-bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the objective-bell of the scope. Naturally, the wind conditions were monitored using a Wind Probe. The set-up was very similar to that pictured below. A 10-shot control group was fired using match-grade hand-loads topped with Sierra 55 grain BlitzKings. The extreme spread of that group measured 0.89”. 
Three 10-shot groups of the Winchester Q3131A1 load were fired in a row. The extreme spreads of those groups measured: 2.95” 3.73” 3.35” for a 10-shot average extreme spread of 3.34”. The three 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 1.05”. The smallest 10-shot group. 
The 30-shot composite group. 
For comparative data, see this thread. |
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Thank you for evaluating this ammo. I've been interested in a quality review of it for some time now.
Is the reason it is "not exactly 'mil-spec'" because it is a tad bit slow (3180fps instead of 3190 - 3270fps? I've run a few boxes through my AR and it seems to function/feed fine. My accuracy was maybe just a bit better (closer to 2" group @ 100yd), but that is probably an individual rifle preference, or just plain luck 
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Coincidentally enough I fired a 10 shot group of Q3131A1 yesterday(the 5th) as well. Same conditions as my post on the Prvi M193 thread. Using a single shot follower. Fired using a 20" Lothar Walther SS 1:8 twist barrel with a Wylde match chamber. Looking through a cheap Bushnell Banner series 4 - 12 x 40 zoomed to 12 power. And before you ask unfortunately I only fired one 10 shot string.
Here is the result: 100 yards using Q3131A1 Lot # PSD09B102-048 09.02.06.16:51 
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Quoted:
And before you ask unfortunately I only fired one 10 shot string. Here's a 10-shot group from 100 yards using IMI M855 fired from a chrome-lined, NATO chambered barrel. Yet when averaged in with two other 10-shot groups the average extreme spread was 2.29". This is why it's important to get an average of at leat three 10-shot groups. We can occaissionly get a group that is the exception, not the rule. Also, using a match-grade barrel instead of a chrome-lined, NATO chambered barrel will sometimes squeeze out a tiny bit more accuracy, (though it's still not going to make a silk purse out of a sow's ear.) 
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