The 1.59-inch Breech-Loading Vickers Q.F. Gun, Mk II, better known as the Vickers-Crayford rocket gun, is a British light artillery piece.
The Vickers-Crayford was manufactured at Vickers' plant in Crayford, England. It was originally supposed to be used in trenches in attacking machine gun positions and pillboxes. However, with the introduction of the trench mortar, the Vickers-Crayford was no longer wanted in the trenches due to trench mortars having a number of advantages over the Vickers-Crayford, including ease of portability, simplicity and low cost among other reasons.
With the Vickers-Crayford no longer wanted in the trenches, it was relegated to anti-vehicle and anti-air roles, and could be loaded with high-explosive, armor-piercing or incendiary shells. The specialized incendiary shells emitted very hot flames from two openings in the base when fired, which gave the weapon its widely popular but misleading name, the Vickers-Crayford rocket gun.
The Vickers-Crayford was also used as an aircraft-mounted weapon to mixed results; a pilot stated that his observer stopped a train after firing about 30 rounds at it, while other squadrons said that there were problems, such as the shell occasionally not leaving the barrel after the striker was released. One occasion even had a loaded shell go off in a shower of sparks after the gunner manning the weapon was going to remove what he thought was a hung round from a supposed misfire. Other than that, the weapon was notorious for having a weak trigger spring, as well as some of the shells having defective primers.
The weapon was hoped to be helpful in taking out German fighters flying across the United Kingdom, and was even planned to be mounted on certain planes. With most plans not coming to fruition about it being a plane-mounted weapon, interest for the Vickers-Crayford waned; its popularity took a heavy hit once incendiary rounds for machine guns were developed for use in air-to-air warfare, making the use of the Vickers-Crayford less desirable. Due to all of these factors, the weapon was completely withdrawn from service by no later than the end of World War I. No surviving examples are known to exist.
The Vickers-Crayford is a breech-loaded artillery piece. Despite being called a "rocket gun", it is incapable of firing rockets, but instead, fires 1.59 inch (40×79mmR) shells. The weapon is loaded by a hinged breech that swings out of the way to the left of the weapon. It was very small and light for a gun for its caliber, which led it to having a low muzzle velocity and a rather short range. The breech was a simple block, and had percussion gear inside it. The Vickers-Crayford was mounted on a non-recoiling frame consisting of a hydraulic buffer, trunnion block and rear guide tube with hand grips mounted on it. The Vickers-Crayford had a big muzzle brake to reduce recoil, but in spite of that, still managed to recoil about 7 to 7.5 inches (17.8 to 19.1 inches).