The .223 Remington (5.56mm NATO)
By Chuck Hawks
The .223 Remington/5.56mm NATO is one of the major success stories of the last half of the 20th century. It is popular world-wide for military and police use and is also very popular in the American civilian market. Most sales charts show it to be in first or second place among all centerfire rifle cartridges. It is chambered for a wide variety of sporting rifles of all types. Ammunition for civilian use is manufactured in Europe and Africa as well as in North America.
The .223 Rem. is basically a .222 Magnum case with a shortened neck and minor changes in some other dimensions. Why the military required these changes I do not know. It was adopted in 1964 by the U.S. military as the 5.56mm NATO, shooting a 55 grain spitzer bullet and introduced to the civilian market as the .223 by Remington in that same year. Like most other centerfire .22's, and despite its ".223" nomenclature, the .223 Remington uses standard .224" diameter bullets. The .223 is loaded to about 52,000 cup.
Whatever one thinks of the 5.56mm NATO as a military cartridge, the .223 Remington is a fine varmint cartridge. It is accurate, gives good barrel life and shoots flat enough for over 90% of all varminting. The availability of inexpensive military and "white box" civilian ammunition makes it economical to shoot, even for those who do not reload. In most areas it is the cheapest of all centerfire rifle calibers for which to buy factory made ammunition.
Some .223 factory loads are extremely accurate, considerably better than military ammunition. One of these is the Remington factory load with the 55 grain Power-Lokt bullet. This is a hollow point spitzer bullet designed specifically for varmint shooting. It has been reported that this bullet will usually group into .5 to .75 inches at 100 yards from a .223 varmint rifle. Most handloaders would be hard pressed to load more accurate ammunition.
Current factory loads drive a 55 grain bullet at 3,240 fps at the muzzle. Muzzle energy is 1,282 ft. lbs. The figures for the Remington 55 grain HP Power-Lokt bullet at 200 yards are 2,352 fps and 675 ft. lbs.
Factory trajectory tables show that a scope sighted .223 shooting the 55 grain spitzer bullet and zeroed at 200 yards hits 1.5" high at 100 yards, 1.5" high at 150 yards, 0 at 200 yards, 3" low at 250 yards, and 7.9" low at 300 yards. The .223 is a 235+ yard varmint cartridge.
The fifth edition of the Nosler Reloading Manual shows that 25.0 grains of H335, the most accurate powder tested, gave a MV of 3140 fps with their 55 grain Ballistic Tip bullets. 25.0 grains of the same powder gave their 60 grain Partition bullet a MV of 3102 fps. Both of these loads were developed in Winchester cases using Remington primers, and were chronographed in a 24" rifle barrel.
The .223 Remington is not a big game cartridge and should not be used for hunting deer and antelope, although it may be legal in certain jurisdictions. Shooting a 55 grain bullet its optimum game weight is only about 19 pounds at 200 yards.
One thing to notice in .223 rifles is the rate of twist. When introduced, military rifles for the .223 had a 1-in-14 twist. Most civilian rifle manufacturers adopted a 1-in-12 twist to stabilize 55 grain bullets to longer ranges. Later, the military replaced the 55 grain bullet with a heavier 62 grain spitzer bullet, and they changed the twist of their rifles to a very fast 1-in-7 inches. Some civilian manufacturers followed suit. According to Speer (the bullet maker) this fast twist is too fast for most lightly constructed varmint bullets when fired at 3,200 fps--they literally come apart in flight. Speer recommends limiting such bullets to a MV of about 2,800 fps in these fast twist barrels. They also note that a 1-in-12 twist gives mediocre accuracy with 62 grain bullets and recommend a 1-in-10 twist for such bullets. A 1-in-10 twist is probably a good compromise for .223 sporting rifles.
Copyright 2001, 2012 by Chuck Hawks. All rights reserved.