The Davis Gun was invented by Commander Cleland Davis, USN, between 1912 and 1914.  It was used during  WWI by the Americans and the British against submarines.  The gun worked on the principal that the recoil from the projectile leaving the barrel of the gun could be cancelled out by the recoil of a counterweight (grease and shot) leaving the back of the gun.  The lack of recoil meant that there was no large shock to the aircraft when the gun was fired.

Schematic of Davis gun firing


6-pounder Davis Projectile (Prototype?) 6-pounder Davis Round (Prototype?)
6-pounder Davis Round 6-pounder Davis Round (Side Primer)
6-Pounder Davis Casing (Bottom) Davis Gun (Reference 1)
Davis Gun (Reference 1) Davis Gun (Reference 1)
Davis Gun (Reference 1) Davis Ammunition (Reference 2)

Davis Ammunition (Reference 2)

Patent Drawing (US Patent Office)


1)     Naval Ordnance Activities World War 1917-1918, 1920, Government Printing Office, Washington D.C.

2)    Ordnance Pamphlet No. 4 Ammunition Instructions for the Naval Service, 1923, Department of the Navy.