20×102mm

Photo coming soon: side view on a transparent background, with author and license.

Key specs

Type: Rifle
Origin: United States
Introduced: 1950
Bullet diameter: 20.00 mm
Typical bullet: 1574.1 gr
Typical velocity: 1,005 m/s
Typical energy: 52,000 J

Sources

Wikipedia (ru): 20 × 102 мм, Wikipedia