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GUNS Magazine January 2013 Digital Edition - Page 22
the .223 remingtOn one of AmeRicA’s moRe AccuRAte And eAsy-to-LoAd foR cARtRidges. JoHn Barsness he .223 Remington appeared in 1964 as the civilian version of the 5.56mm NATO. The 5.56mm itself was essentially a compromise between the .222 Remington (1950) and .222 Remington Magnum (1958) for use in the US military’s new M16 rifle. The cases of the .223 and 5.56 are essentially identical, but the chamber throat of 5.56 rifles is longer, and the pressures of military ammo are usually higher as well. Consequently it’s generally considered safe to fire commercial .223 ammo in 5.56mm chambers, but not the reverse. Also, 5.56 rifles generally have faster rifling twists, and some (though not all) military cases are heavier than commercial brass. Military primers also have heavier cups, to withstand higher pressure and the slam of automatic fire, especially in a hot rifle. Some longer bullets had conventional lead cores, while others were longer due to using “non-toxic” materials, for the entire bullet or just the cores. The .223 is normally very accurate, especially in heavy-barreled varmint rifles, and the AR-15 is now just as accurate as many bolt actions. T FiVe test riFles The data listed was fired in five different rifles, three bolt actions with .223 chambers and two AR-15s with 5.56 chambers. Barrel lengths varied from 16" to 26", providing a general idea of how length affected muzzle velocity. Several newer powders were tested in the newest pair of the rifles, a Thompson/Center Icon .223 with a heavy 22" barrel and a 1:12" twist, and one of the brand-new Nosler/ twist Until recently, the barrels on just about all commercial rifles had rifling twists of 1-turn-in-12" (1:12"), the same as the original M16 adopted by the US military. This stabilizes leadcored spitzers up to about 60 grains, and since most hunters used 40- to 55-grain bullets in the .223, the twist worked fine—and still does, when handloading conventional varmint bullets. The military eventually increased bullet weights in some 5.56mm ammunition to increase effectiveness in various combat situations. In a few M16 variations the twist rate was changed to 1:7", capable of stabilizing leadcored spitzers up to 80+ grains in weight. At the same time more American hunters wanted to use longer bullets, both for varmint shooting at longer ranges and for hunting smaller big game such as deer and feral pigs. 22 Noveske Varmageddon AR-15s with a 5.56 chamber in an 18" match barrel with a 1:8" twist. I hadn’t tried any handloads in the Nosler rifle, but it averaged about .6" for five shots at 100 yards with Nosler Varmageddon ammo. It turned out to be tough to match that with handloads! The .223 is remarkably easy to handload, and usually very accurate. Until a decade ago, almost all the varmint shooters I knew used Hodgdon H335 ball powder, because it metered very precisely (handy when loading lots of ammo) and resulted in fine accuracy and top velocities. However, it also burned somewhat dirty, back then considered a necessary evil of ball powders, due to coatings that resisted burning just enough to slow burn rate. (In extruded powders, granule size is also used to slow burn rate, a technique obviously not applicable to ball powder.) As a result, it was considered mandatory to give bores at least a cursory field cleaning after 50 or 75 rounds, and to really scrub them each evening after the day’s shooting was done, the reason many older PD shooters associate the smell of Hoppe’s No. 9 and freshly opened Budweiser. In the early 1990s, Hodgdon ran out of the original military-surplus powder they sold as H335, and replaced it with newly made powder. If you still have a bunch of the older powder, it will probably result in slower velocities. I used to use 28.0 grains of old H335 with 50-grain bullets, but the new powder reached the same velocity with 2 grains less powder. Clean Burning The rifles used in testing recent powders were a Nosler/Noveske Varmageddon AR-15 and a Thompson/Center Icon Precision Hunter. Several of today’s ball powders burn cleaner. A dozen years ago, I was invited on a prairie dog shoot in eastern Montana with a company called W W W. G U N S M AG A Z I N E . C O M • JA N UA RY 2 0 1 3