20×110mm USN

It is not interchangeable with any other 20×110mm cartridge.

• Name — 20×110mm USN • Type — Autocannon • Service — 1950s–present • Used By — United States Navy Royal New Zealand Air Force • Wars — Vietnam War • Designer — United States Navy • Is Si Specs — yes • Case Type — Rimless, bottleneck • Bullet — 19.9 • Neck — 20.6 • Base — 29 • Rim Dia — 29.5 • Case Length — 109.5 • Length — 185 • Primer — Electric • Max Pressure — 600 • Is Si Ballistics — no • Bwunit — gr • Bw1 — 1700 • Btype1 — Mk 105 HEI • Vel1 — 1010 • En1 — 56,105 j

Some of the available loads for the 20×110mm USN are as follows: • Name — Pressure (PSI) — Projectile weight (grains) — Projectile Type — Muzzle Velocity (fps) — Identification • Cartridge, 20 mm, High Pressure Test (HPT), Mk 101 Mod 0 (USN) — Not to exceed 72,500 — 1700 — Inert — Not listed — Green or blue projectile with brown nose and 1/4 black letters reading "High pressure test round" • Cartridge, 20 mm, Low Pressure Test (LPT), Mk 102 Mod 0 (USN) — Not listed — 1700 — Inert — Not listed — Green or blue projectile with brown nose and 1/4 black letters reading "Low pressure test round" • Cartridge, 20 mm, Dummy, MK 103 (USN) — n/a — 1700 — Inert — n/a — No primer or propellant, MK11 brown projectile. • Cartridge, 20 mm, Target Practice (TP), Mk 105 Mod 0 (USN) — Not to exceed 72,500 — 1700 — Inert — 3350 — Green or blue projectile black lettering or blue projectile with brown nose and black lettering • Cartridge, 20 mm, High Explosive Incendiary (HEI), Mk 106 Mod 0 & 1 (USN) — 60,000 — 1700 ±50 — Impact detonating — 3350 — Unpainted fuze, red and yellow projectile • Cartridge, 20 mm, Armor-Piercing Incendiary (API), Mk 107 Mod 0 (USN) — 60,000 — 1700 ±50 — Armor-piercing incendiary — 3350 — No fuze, nose of projectile blue or brown with red band. Body of projectile black with white lettering. • Cartridge, 20 mm, Armor-Piercing Tracer (AP-T), Mk 108 Mod 0 (USN) — 60,000 — 1700 ±50 — Armor-piercing tracer — 3350 — No fuze. Hollow windshield. Brown or yellow nose, body of projectile black with white lettering. • Cartridge, 20 mm, Firing Circuit Test, MK109 (USN) — n/a — n/a — n/a — n/a — Used for electric firing circuit tests, no projectile There is also a cartridge, 20 mm, dummy, Mk 103 Mod 0 (USN) which is an inert round. It has an empty primer pocket and holes in the case or a plugged primer pocket. It may be empty or filled with inert material. The projectile is usually brass or bronze plated.