.22 Spitfire
.22 Spitfire with FN 5.7×28mm and .30 Carbine cartridges
Type Rifle
Place of origin USA
Production history
Designer Melvin M. Johnson
Designed 1963
Manufacturer Johnson Guns Inc.
Bullet diameter .224 in (Bad rounding hereScript error mm)
Neck diameter .253 in (Bad rounding hereScript error mm)
Shoulder diameter .332 in (Bad rounding hereScript error mm)
Base diameter .353 in (Bad rounding hereScript error mm)
Rim diameter .356 in (Bad rounding hereScript error mm)
Case length 1.29 in (Bad rounding hereScript error mm)
Overall length 1.65 in (Bad rounding hereScript error mm)
Rifling twist 1:14
Primer type Boxer small rifle
Ballistic performance
Bullet weight/type Velocity Energy
40 gr (Bad rounding hereScript error g) 2,850 ft/s (Bad rounding hereScript error m/s)720 ft·lbf (Bad rounding hereScript error J)
40 gr (Bad rounding hereScript error g) 3,000 ft/s (Bad rounding hereScript error m/s)795 ft·lbf (Bad rounding hereScript error J)
50 gr (Bad rounding hereScript error g) 2,700 ft/s (Bad rounding hereScript error m/s)810 ft·lbf (Bad rounding hereScript error J)
Source(s): Barnes & Amber

The .22 Spitfire (also known as 5.7mm Johnson or MMJ 5.7mm Johnson[1]) is an American rifle cartridge.

Designed by Melvin M. Johnson of Johnson Guns Inc. for their conversion of the M1 carbine,[2] this wildcat[3] was introduced in 1963. It was based on the .30 carbine, necked-down to .22 (5.7mm).[4]

It is suitable for rabbits, coyotes, or other varmints,[4] and has potential as a military round.[4]

See alsoEdit


  1. Script error
  2. Barnes, Frank C., ed. by John T. Amber. Cartridges of the World (Northfield, IL: DBI Books, 1972), p.127.
  3. Barnes and Amber, p.127.
  4. 4.0 4.1 4.2 Barnes and Amber, p.127.


  • 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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