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.22 Spitfire

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.22 Spitfire
.22 Spitfire with FN 5.7×28mm and .30 Carbine cartridges
TypeRifle
Place of originUSA
Production history
DesignerMelvin M. Johnson
Designed1963
ManufacturerJohnson Guns Inc.
Specifications
Parent case.30 Carbine
Bullet diameter.224 in (5.7 mm)
Neck diameter.253 in (6.4 mm)
Shoulder diameter.332 in (8.4 mm)
Base diameter.353 in (9.0 mm)
Rim diameter.356 in (9.0 mm)
Case length1.29 in (33 mm)
Overall length1.65 in (42 mm)
Rifling twist1:14
Primer typeBoxer small rifle
Ballistic performance
Bullet mass/type Velocity Energy
40 gr (3 g) 2,850 ft/s (870 m/s) 720 ft⋅lbf (980 J)
40 gr (3 g) 3,000 ft/s (910 m/s) 795 ft⋅lbf (1,078 J)
50 gr (3 g) 2,700 ft/s (820 m/s) 810 ft⋅lbf (1,100 J)
Source(s): Barnes & Amber

The .22 Spitfire (Originally the Johnson MMJ 5.7mm Spitfire,[1] also known as 5.7mm Johnson or 5.7mm MMJ[2]) is an American wildcat rifle cartridge developed by Melvin Johnson.

In 1963, firearms designer Melvin Johnson developed a conversion of the M1 Carbine to the Johnson MMJ 5.7mm Spitfire Cartridge,[3][4] The cartridge[5] is based on the .30 Carbine cartridge, necked-down to .224 (5.7 mm) caliber.[5][6] Originally designed with a 1-in-14 twist barrel, the 40 grain .22 Hornet bullet was the standard load. It could also be loaded with lighter or heavier weight bullets available at that time for the .22 Hornet as well as most bullet weights up to 50 grains such as that used by the .222 Remington (5.7×43mm).[7]

The conversion is essentially a .22 caliber (5mm) barrel fitted to an M1 Carbine receiver with an appropriate feed ramp for the caliber brazed or welded into the receiver. Some commercial production M1 Carbines were originally manufactured in this caliber with the feed ramp for the .22 Spitfire integral to the barrel.[8]

The specifications tend to land the cartridge about halfway between the 5.56×45mm NATO and the more recent 5.7x28mm FN.[9] Ballistically it is very similar to the rimmed .22 Hornet, but fashioned in a rimless cartridge design appropriate for a self-loading carbine with very light recoil. The Spitfire M1 Carbine originally was advertised as firing a 40-grain (2.6g) bullet with a muzzle velocity of 3050 ft/s (930 m/s), though handloaders with careful selection of modern powders and appropriate bullets consistently safely exceed those numbers while remaining within the M1 Carbine's Maximum Pressure rating of 38,500 psi (265 MPa).[10] In comparison, the "standard" load for the .30 Carbine has a .30 Carbine ball bullet weighing 110 grains (7.1 g); a complete loaded round weighs 195 grains (12.6 g) and has a muzzle velocity of 1,990 ft/s (610 m/s), giving it 967 ft⋅lbf (1,311 joules) of energy when fired from the M1 carbine's 18-inch barrel.[11]

Johnson advertised the smaller caliber and the modified carbine as a survival rifle for use in jungles or other remote areas. It was light, and easily carried ammunition in a light, fast handling carbine with low recoil.[12][13]

See also

Notes

  1. ^ "The Johnson Spitfire Rifle". www.johnsonautomatics.com.
  2. ^ "Reloading Quick Reference - Reloading". Cheaperthandirt.com. Archived from the original on 2012-03-14. Retrieved 2012-05-22.
  3. ^ "The Johnson Spitfire Rifle". www.johnsonautomatics.com. Retrieved 17 February 2021.
  4. ^ Barnes, Frank C., ed. by John T. Amber. Cartridges of the World (Northfield, IL: DBI Books, 1972), p.127.
  5. ^ a b Barnes and Amber, p.127.
  6. ^ Woodard, W. Todd (2016). Cartridges of the World: A Complete and Illustrated Reference for Over 1500 Cartridges. Gun Digest Books. ISBN 978-1-4402-4648-7.
  7. ^ Barnes, Frank C., ed. by John T. Amber. Cartridges of the World (Northfield, IL: DBI Books, 1972), p.127.
  8. ^ "The Johnson Spitfire Rifle". www.johnsonautomatics.com.
  9. ^ Woodard, W. Todd (2016). Cartridges of the World: A Complete and Illustrated Reference for Over 1500 Cartridges. Gun Digest Books. ISBN 978-1-4402-4648-7.
  10. ^ "Reloading Data 5.7mm Johnson Metallic".
  11. ^ "Shooter's Reference Load Data for".
  12. ^ "The Johnson Spitfire Rifle". www.johnsonautomatics.com.
  13. ^ Barnes, Frank C., ed. by John T. Amber. Cartridges of the World (Northfield, IL: DBI Books, 1972), p.127.

References

  • Barnes, Frank C., ed. by John T. Amber. "MMJ-5.7mm", in Cartridges of the World, pp. 127 & 143. Northfield, IL: DBI Books, 1972. ISBN 0-695-80326-3.


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