.223 Remington

Infobox Firearm Cartridge
name=.223 Remington


caption= .223 Rem (left) next to .30-30 (center) and .308 (right)
origin=flagcountry|United States
type=Rifle/varmint
designer=Remington Arms
design_date=1964
variants=.223 Ackley Improved, 5.56x45mm NATO
parent=.222 Remington Magnum
case_type=Rimless, bottleneck
bullet=.224
neck=.253
shoulder=.354
base=.376
rim_dia=.378
rim_thick=.045
case_length=1.76
length=2.26
rifling=1/12" (typical)
primer=Small rifle
bw1=36
btype1= JHP
vel1=3750
en1=1124
bw2=55
btype2=Nosler ballistic tip
vel2=3240
en2=1282
bw3=60
btype3=Nosler partition
vel3=3160
en3=1330
bw4=69
btype4=BTHP
vel4=2950
en4=1333
bw5=77
btype5=BTHP
vel5=2750
en5=1293
test_barrel_length=24 in.
balsrc= Federal Cartridge cite web |url=http://www.federalcartridge.com/ballistics/ |title=Federal Cartridge Co. ballistics page |accessdate=2007-09-25 ]

The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a convert|0.224|in|mm|sing=on diameter, jacketed bullet, with weights ranging from 40 up to convert|90|gr, though the most common loading by far is convert|55|gr.

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. [cite web |url=http://www.frfrogspad.com/miscelld.htm#5.56%20mm%20NATO |title=Miscellaneous Questions 4] 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. [cite web |url=http://www.accuratepowder.com/data/PerCaliber2Guide/Rifle/Standarddata(Rifle)/22Cal(5.56mm)/223%20Remington%20pages%20185%20to%20187.pdf |title=.223 Remington |author=Accurate Powder]

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 Armalite AR-15, a version of which later became the U.S. military's M16 rifle.

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 40 and convert|60|gr, 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-12, or 1-in-9. (Most modern AR-15s use 1-in-9 which is suitable for bullets up to convert|75|gr 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.) The semi-automatic rifle category is often used by law enforcement, for home defense, and for varmint hunting (especially farm and ranch work, after which Ruger named a version of its Mini-14 the "Ranch Rifle"). 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

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for chamber, which are designed to handle both 5.56 mm and .223 equally well.

Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive lead. [cite web |url=http://www.winchester.com/lawenforcement/news/newsview.aspx?storyid=11 |title=Winchester News and Press Releases, .223 Rem VS 5.56 mm |accessdate=2007-09-25 ] Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle and may even be unsafe, and the SAAMI recommends against the practice. [cite web |url=http://www.thegunzone.com/556v223.html |title=5.56mm v. 223 Remington |accessdate=2007-09-25 ] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14 [cite web |url=http://www.ruger.com/Firearms/PDF/InstructionManuals/55.pdf |title=Instruction manual for Ruger Mini-14 Ranch Rifle |accessdate=2007-12-21] , 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 5.56 mm ammunition.

Related cartridges

P.O. Ackley created an improved version of this cartridge called the .223 Ackley Improved. [cite web | url=http://findarticles.com/p/articles/mi_m0BQY/is_4_49/ai_98124201 | title=Pumping up the .223: experiments with a self-loading .223 Ackley Improved | accessdate=2008-06-10 | date=April 2003 | author=Dave Anderson | publisher=Guns Magazine] 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 convert|100|ft/s|m/s|abbr=on faster velocities.Fact|date=October 2008

Wildcat cartridge developers have long-necked this cartridge up to create the 6mm/223 or 6x45. 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 6 mm BR Remington.Fact|date=October 2008

ee also

* List of rifle cartridges
* 5 mm caliber
* Delta L problem

References

External links

* [http://www.6mmbr.com/223rem.html .223 Remington Cartridge Guide] by AccurateShooter.com
* [http://www.ammo-oracle.com/ AR15 Ammo Oracle] by Troy Tiscareno
* [http://www.thegunzone.com/556dw.html A 5.56x45mm "Timeline"] by Daniel Watters