In the automatic pistol, the recoil from the explosion drives the working part of the pistol back against a strong spring. As soon as the force of the explosion is spent, this spring forces the working parts back into place again. These working parts do all the work the shooter does in a single-shot pistol—that is, it cocks the pistol, opens the breech, extracts the spent cartridge, inserts a fresh cartridge, and closes the breech.
The idea is very simple, and has occurred to almost everyone who has handled a pistol or a rifle, but there are mechanical difficulties which are only just beginning to be overcome, and the automatic pistol, and still more the automatic rifle, are yet far from perfect.
The chief difficulty is the force of the explosion. In a motor-car engine, the force of each explosion can be regulated so as to be just sufficient for the work required.
In an automatic pistol this cannot be done. The force of the explosion is that which gives the best shooting, in other words the greatest possible force, subject to the shooter being able to stand the recoil and the pistol not to burst, though made light enough to be easily handled.
If a pistol were made a ton weight, it would fire a very much larger charge without bursting, but the charge of the explosion has to be limited to what a pistol of some two and a half pounds’ weight can bear without bursting, or recoiling too severely on the shooter.
The smaller pocket automatic pistols are lighter (the two-and-a-half pound ones are military pistols).
A pistol weighing under two and a half pounds can shoot only a small charge with light recoil, and so is easier to make.
The heavy recoil from a military rifle (which gives the bullet a speed of some thirty thousand feet a second) would shatter the recoil mechanism of a small pocket pistol, though the latter can quite safely operate under the slight recoil of its weak cartridge.
With a magazine rifle or revolver, the shooter uses just sufficient manual force to operate the mechanism, and even then pistols and rifles may get damaged by a clumsy man using too much force to wrench the weapon open or slam it shut.
If, instead of the intelligently applied strength of a man, using the minimum force necessary, you substitute the smashing blow (several tons’ weight to the square inch) given by the force of gunpowder, to operate delicate mechanism, you can realize the difficulty the inventor has to contend with.