圖中5.56mm NATO,30-30,7.62x51mm 前NATO子彈
223 Remington
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.223 Remington
Designed 1964
Variants .223 Ackley Improved, 5.56x45mm NATO
Specifications
Parent case .222 Remington Magnum
Case type Rimless, bottleneck
Bullet diameter 0.224 in (5.7 mm)
Neck diameter 0.253 in (6.4 mm)
Shoulder diameter 0.354 in (9.0 mm)
Base diameter 0.376 in (9.6 mm)
Rim diameter 0.378 in (9.6 mm)
Rim thickness 0.045 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).
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.[2] 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.[3]
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.
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本帖最後由 MS 於 26-7-2009 02:43 編輯 ]
