Recoil has always been a big problem in the history of gun development, it not only affects the accuracy and frequency of shooting, but also increases the complexity of the structure, although designers have come up with many ways to weaken the impact of recoil, but it is basically impossible to achieve a perfect effect. However, in the entire history of gun development, there was once such a gun that did reduce the impact of recoil to a very low value, which is the Douglas recoilless submachine gun in Canada.
The Douglas submachine gun began to be designed in the late 1960s, the first prototype gun was delivered to the Canadian Army in 1973 for testing, although it was not adopted, it is still a very technical equipment, today we will briefly introduce it.
The Douglas submachine gun is a small weapon that can be held with one hand or both hands, it does not have a stock, because it is easy to grasp it does not require a stock, its principle of "recoillessness" is not complicated, the bolt and barrel can be moved separately, and the two parts are connected by springs.
When the ammunition is fired, under the action of pressure, the shell pushes the bolt backwards, while the barrel rushes forward, at this time the bolt and the barrel breech are separated to create a gap, the empty shell is ejected, due to the spring action between the bolt and the barrel, the two move to a certain extent and are pulled back to re-tighten, this bonding process is also accompanied by a new ammunition load.
This principle is very similar to the early recoilless guns with counterweight blocks, the bolt acted as a counterweight when shooting, which greatly reduced the firing recoil, and the Douglas submachine gun could hold the strafing in one hand, which is why it was called a recoilless submachine gun.
However, it is not without recoil, but the use of a special structure to offset most of the recoil on the shooter, while the effect of ammunition out of the chamber is still there, so there is still a certain upward movement in the muzzle.
Another highlight of the Douglas submachine gun's feed structure is that it does not use a conventional magazine or drum, but is a rotating cartridge similar to the Bison submachine gun, with 9×19 mm bullets arranged in a spiral arrangement with a capacity of 50 rounds, and the cartridge is inserted obliquely from above the grip. The cartridge itself has no spring parts, and its feed needs to rely on the shaft movement in the middle of the cartridge during the backward movement of the bolt when shooting, so as to complete a toggle forward to push the ammunition.
This specially designed feed has its advantages, its movement can offset part of the force of the bolt movement, can reduce the bolt movement range, but with the consumption of ammunition, the force required to complete a movement in the cartridge is also reduced, which is bound to affect the shooting of the gun.
Submachine gun shooting movement process will also have a certain impact on the power, we know that although the recoilless gun is called a cannon, but its ammunition flight speed is far less than that of a conventional barrel gun, the reason is that the air flow sprayed backwards reduces the chamber pressure, the Douglas submachine gun also has the same problem, the gas burned by the bullet propeller in the expansion process to push the bolt, the barrel moves in the opposite direction, gradually increasing and opening the space is not conducive to the chamber pressure increase, so compared to the same type of firearm its bullet rate may be lower, The impact of such a structure for rifles may be more pronounced.
After testing and comparison, the Canadian Army believes that the Douglas recoilless submachine gun is less reliable than conventional submachine guns, its innovation has not been recognized, and it is difficult to find more information about the gun on the Internet.