Description Three US Navy WW II Era Oerlikon 20mm All-Up Rounds. 1) Projectile and cartridge. Primer missing. Projectile nose cap marked with Mk 26 ..NC .. Projectile body is marked with MK 3-26 F L2-42 Cartridge base is marked with AG 1942 20MM MK 2 2) Projectile and cartridge. Primer missing. Red paint on body of projectile (Indicates Tetryl filler). Projectile nose cap is marked with Mk 26-1 AM Projectile body is marked with MK 3 - 42 - H - 8 - 43 Cartridge base is marked with 20 MM MK 2 1943 3) Projectile and cartridge. Primer present. Primer has been fired. Projectile nose cap is marked with MK 26 ME 553 Projectile body is marked with HOSDREG 20 MM MK 3 MOD 8 3-42 Projectile base is marked with 20 MM MK 2 MS 1942