.223 Remington

.223 Remington
30-30.jpg
5.56x45mm NATO (left) next to .30-30 Winchester (center) and 7.62x51mm NATO (right)
Type Rifle/varmint
Place of origin  United States
Production history
Designer Remington Arms
Designed 1964
Variants .223 Ackley Improved, 5.56x45mm NATO
Specifications
Parent case .222 Remington Magnum
Case type Rimless, bottleneck
Bullet diameter .224 in (5.7 mm)
Neck diameter .253 in (6.4 mm)
Shoulder diameter .354 in (9.0 mm)
Base diameter .376 in (9.6 mm)
Rim diameter .378 in (9.6 mm)
Rim thickness .045 in (1.1 mm)
Case length 1.76 in (45 mm)
Overall length 2.26 in (57 mm)
Rifling twist 1 in 12 in (typical)
Primer type Small rifle
Maximum pressure 55,000 psi (380 MPa)
Ballistic performance
Bullet weight/type Velocity Energy
36 gr (2.3 g) JHP 3,750 ft/s (1,140 m/s) 1,124 ft·lbf (1,524 J)
55 gr (3.6 g) Nosler ballistic tip 3,240 ft/s (990 m/s) 1,282 ft·lbf (1,738 J)
60 gr (3.9 g) Nosler partition 3,160 ft/s (960 m/s) 1,330 ft·lbf (1,800 J)
69 gr (4.5 g) BTHP 2,950 ft/s (900 m/s) 1,333 ft·lbf (1,807 J)
77 gr (5.0 g) BTHP 2,750 ft/s (840 m/s) 1,293 ft·lbf (1,753 J)
Test barrel length: 24 inches (61 cm)
Source: Federal Cartridge [1]

The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56x45mm NATO military cartridge. The name is pronounced either two-two-three or two-twenty-three. It is loaded with a 0.224-inch (5.7 mm) diameter, jacketed bullet, with weights ranging from 40 to 90 grains (2.6 to 5.8 g), though the most common loading by far is 55 grains (3.6 g). When loaded with a bullet that expands, tumbles, or fragments in tissue, this cartridge is capable of delivering devastating terminal performance, including remote wounding effects known as hydrostatic shock.[2][3][4]

While the external case dimensions are very similar, the .223 Remington and 5.56x45mm differ in both maximum pressure and chamber shape. The maximum and mean pressures for some varieties of the 5.56 mm (different cartridge designations have different standards) exceed the SAAMI maximums for the .223 Remington, and the methods for measuring pressures differ between NATO and SAAMI.[5] The 5.56 mm chamber specification has also changed over time since its adoption, as the current military loading (NATO SS-109 or US M855) uses longer, heavier bullets than the original loading did. This has resulted in a lengthening of the throat in the 5.56 mm chamber. Thus, while .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, firing 5.56 mm ammunition in a .223 Remington chamber may produce pressures in excess of even the 5.56 mm specifications due to the shorter throat.[6]

Contents

History

The .223 Remington was developed as an enlarged and higher velocity version of the .222 Remington, which was introduced in 1950 as a varmint cartridge. The .223 Remington was developed specifically for the AR-15, a version of which later became the U.S. military's M16 rifle.

Cartridge dimensions

The .223 Remington has 1.87 ml (28.8 grains H2O) cartridge case capacity.

.223 Remington.jpg

.223 Remington maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).[7]

Americans would define the shoulder angle at alpha/2 = 23 degrees. The common rifling twist rate for this cartridge is 305 mm (1 in 12 in), 6 grooves, Ø lands = 5.56 millimetres (0.219 in), Ø grooves = 5.59 millimetres (0.220 in), land width = 1.88 millimetres (0.074 in) and the primer type is small rifle.

According to the official Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives (C.I.P.) guidelines the .223 Remington case can handle up to 430 megapascals (62,366 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. This is equal to the NATO maximum service pressure guideline for the 5.56x45mm NATO cartridge.

The SAAMI pressure limit for the .223 Remington is set at 379.212 megapascals (55,000 psi), piezo pressure.[8]

Uses

The .223 Remington is one of the most common rifle cartridges in use in the United States, being widely used in two types of rifles: (1) varmint rifles, most of which are bolt action and commonly have 1-in-12 rifling twist suitable for bullets between 38 to 55 grains (2.5 to 3.6 g), and (2) semi-automatic rifles such as the AR-15 and the Ruger Mini-14, which are commonly found to have twist rates of 1-in-7, 1-in-9, or 1-in-8. (Most modern AR-15s use 1-in-9 which is suitable for bullets up to 69 grains / 4.5 grams or 1-in-7 which is suitable for slightly heavier bullets, but older AR-15s used 1-in-12 twist rates, making them suitable for use with bullets of 55 grains / 3.6 grams.) The semi-automatic rifle category is often used by law enforcement, for home defense, and for varmint hunting. Among the many popular modern centerfire rifle cartridges, .223 Remington ammunition is among the least expensive and is often used by avid target shooters, particularly in the "high power rifle" category.

.223 Remington versus 5.56 mm NATO

These 5.56x45mm NATO cartridges are identical in appearance to .223 Remington. They are, however, not completely interchangeable.

While the 5.56mm NATO and .223 Remington cartridges and chamberings are very similar, they are not identical.

Military cases are generally made from thicker brass than commercial cases; this reduces the powder capacity (an important consideration for handloaders[9]), and the NATO specification allows a higher chamber pressure. NATO EPVAT test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the location used by the United States civil standards organization SAAMI. The piezoelectric sensors or transducers NATO and SAAMI use to conduct the actual pressure measurements also differ. This difference in measurement method accounts for upwards of 137.9 megapascals (20,000 psi) difference in pressure measurements. This means the NATO EPVAT maximum service pressure of 430 megapascals (62,000 psi) for 5.56mm NATO, is reduced by SAAMI to 379.21 megapascals (55,000 psi) for .223 Remington.[10] In contrast to SAAMI, the other main civil standards organization C.I.P. defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56mm NATO.

The 5.56mm NATO chambering, known as a NATO or mil-spec chamber, has a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 Remington chambering, known as SAAMI chamber, is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber (Rock River Arms)[11] or the ArmaLite chamber, which are designed to handle both 5.56mm NATO and .223 Remington equally well. The dimensions and leade of the .223 Remington minimum C.I.P. chamber also differ from the 5.56mm NATO chamber specification.

Using commercial .223 Remington cartridges in a 5.56mm NATO chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223 Remington chambered gun due to the longer leade.[12] Using 5.56mm NATO mil-spec cartridges (such as the M855) in a .223 Remington chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[13][14] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56mm NATO, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56mm NATO ammunition.[15]

Related cartridges

P.O. Ackley created an improved version of this cartridge called the .223 Ackley Improved.[16] It has the straight sides and steep shoulder typical of the Ackley design improvements, yielding about 5% extra case volume. This in turn provides longer case life, less stretching, and up to 100 ft/s (30 m/s) faster velocities.

Wildcat cartridge developers have for a long time necked this cartridge up to create the 6mm/223 or 6×45. At one time this round was very popular for varminting and competition but has been replaced by current popular competition cartridges using short fat cases, such as the 6 mm PPC and the 6mm Norma BR.

See also

References

  1. ↑ "Federal Cartridge Co. ballistics page". http://www.federalcartridge.com/ballistics/. Retrieved 2007-09-25. 
  2. ↑ Chamberlin FT, Gun Shot Wounds, in Handbook for Shooters and Reloaders, Vol. II, Ackley PO, ed., Plaza Publishing, Salt Lake City, Utah, 1966.
  3. ↑ Courtney A, Courtney M: Links between traumatic brain injury and ballistic pressure waves originating in the thoracic cavity and extremities. Brain Injury 21(7): 657-662, 2007. http://arxiv.org/ftp/arxiv/papers/0808/0808.1443.pdf
  4. ↑ Scientific Evidence for Hydrostatic Shock http://arxiv.org/ftp/arxiv/papers/0803/0803.3051.pdf
  5. ↑ "Miscellaneous Questions 4". http://www.frfrogspad.com/miscelld.htm#5.56%20mm%20NATO. 
  6. ↑ Accurate Powder. ".223 Remington" (PDF). http://www.accuratepowder.com/data/PerCaliber2Guide/Rifle/Standarddata(Rifle)/22Cal(5.56mm)/223%20Remington%20pages%20185%20to%20187.pdf. 
  7. ↑ C.I.P. decisions, texts and tables free current C.I.P. CD-ROM version download (ZIP and RAR format)
  8. ↑ "SAAMI Pressures". http://www.leverguns.com/articles/saami_pressures.htm. Retrieved 2007-11-29. 
  9. ↑ Accurate Powder Co.. ".223 Remington handloading data". http://www.accuratepowder.com/data/PerCaliber2Guide/Rifle/Standarddata(Rifle)/22Cal(5.56mm)/223%20Remington%20pages%20185%20to%20187.pdf. 
  10. ↑ "SAAMI Pressures". http://www.leverguns.com/articles/saami_pressures.htm. Retrieved 2007-09-25. 
  11. ↑ Rock River Arms
  12. ↑ Winchester
  13. ↑ "Unsafe Arms and Ammunition Combinations" at SAAMI web site Accessed 2009-03-09. Archived 2009-04-19.
  14. ↑ The Gun Zone
  15. ↑ [1]
  16. ↑ Dave Anderson (April 2003). "Pumping up the .223: experiments with a self-loading .223 Ackley Improved". Guns Magazine. http://findarticles.com/p/articles/mi_m0BQY/is_4_49/ai_98124201. Retrieved 2008-06-10. 

External links