the pistol. A spring returns the extractor to its place when the
empty cartridge cases have been ejected, and brings the barrel
to an angle of about 45°, for convenience in loading. The
soundness and rigidity of the weapon depend upon the efficiency
of the connexion between the barrels and the standing breech,
and a top snap bolt has proved the strongest and handiest with
the pistol, as with the shot-gun.
This type of revolver originated with Messrs Smith & Wesson, but they and other gun makers have greatly improved upon the original model. Between the American pattern and the English, as made by Messrs F. Webley & Son, the chief difference is that in the Smith & Wesson the holding-down bolt or catch is upon the barrel, and it engages with the top of the standing breech, whereas in the Webley the bolt is upon the standing breech and grips the extremity of the hinged barrel. Neither mechanism is as strong as could be wished if heavy charges of smokeless nitro-compounds are to be used. This hinged type of revolver is most convenient for use on horseback, as the pistol can be opened, the cartridges extracted and the weapon reloaded with one hand.
 |
| Fig. 5—Percussion-lock pistol (Royal United Service Institution). |
The Colt’s Double-action Revolver, calibre ·38, model 1896, used in the United States army, consists (figs. 7 and 8) of the barrel (B), the cylinder (C) with six chambers, the frame (F), and the firing mechanism, all of steel. The muzzle velocity, with a charge of 16 grains of black powder and a bullet of 150 grains of lead, is about 708 ft. per second, giving at 25 yards a penetration of about 5 in. in pine.
The lock mechanism consists of the hammer (h), with its stirrup (r), stirrup pin (p), strut (s), strut pin (i), strut spring (g); the trigger (t); the rebound lever (l); the hand (a), with the spring (z); the cylinder bolt (b), with its spring (x); the locking ever (v); the main spring (m), and rebound lever spring (n). The hammer (h), trigger (t), and rebound lever (l) are pivoted on their respective pins, which are fastened in the left side of the frame. The lower end of the rebound lever spring (n) is secured to the frame and the free end bears under the rear end of the rebound lever so that the latter, when the trigger is released, cams the hammer back to its safety position, and forces the trigger forward. Pressure upon the trigger causes its upper edge to engage the strut, and thereby raises the hammer until nearly in the full-cock position, when the strut will escape from the trigger, and the hammer, under the action of the main-spring, will fall and strike the cartridge. A projection on the upper part of the trigger, working in a sot in the frame, prevents the cylinder from making more than one-sixth of a revolution at a time by entering one of the grooves nearest the rear end of the surface of the cylinder. When the cylinder is swung out of the frame, the arts are arranged to prevent the cocking of the hammer. The cylinder bolt is pivoted on the trigger pin, and its spring, bearing on the rebound lever arm, causes the nose of the bolt to project through a slot in the frame ready to enter one of the rectangular cuts in the cylinder surface. During the first movement of the trigger in cocking the revolver, the nose of the bolt is withdrawn, allowing free rotation of the cylinder. The object of the bolt is to prevent rotation of the cylinder in transportation The hand is attached by its pivot to the trigger, and, as the latter swings on its pin when the hammer is being cocked, the hand is raised and revolves the cylinder, and also serves to lock the cylinder in position at the time of firing. An abutment on the side plate supports the hand spring in rear The spring ensures the engagement of the hand with the ratchet (y). The revolver is cocked by hand by withdrawing the hammer by the pressure of the thumb until its full-cock notch engages in the rear sharp corner of the trigger. Pulling the trigger then releases the hammer, allowing its firing pin (f) to move forward and strike the cartridge.
The locking lever is pivoted by its screw in a recess in the left side of the frame, and so connected with the latch that it locks the hammer and trigger when the latch is pushed to the rear for opening the cylinder, and does not unlock them until the cylinder is positively closed and is locked by the latch The cylinder revolves and is supported on a central arbour of the crane (E). The crane fits in a recess in the frame below the barrel and turns on its pivot arm (A). The ejector rod with its spring passes through the centre of the cylinder arbour and is terminated in rear by the ejector with a ratchet (y). Pushing against the front end of the ejector rod will empty the chambers, the cylinder being swung out for loading The thumb-piece of the latch (j) slides to the rear in the left side of the frame, unlocking the cylinder for opening, but upon closing the cylinder, the body of the latch firmly enters a recess in the ejector, locking the cylinder in position for firing.
 |
| Fig. 6.—Pepper-box revolver. |
One great disadvantage of revolvers is the escape of gas at the opening between the breech of the barrel and the cylinder. This escape corrodes the surrounding parts and also materially diminishes the pressure in the barrel and the consequent velocity of the bullet. In the Nagant revolver, adopted by Russia, this disadvantage has been overcome by employing a long cartridge case which extends beyond the nose of the bullet and bridges the gap between barrel and cylinder as the cylinder is moved forward. A “mitrailleuse” pistol has also been constructed by the Braendlin Armoury Co., Ltd., on the “pepper-box” principle, with fixed barrels, either four or six, arranged in pairs, and a special striking mechanism, in which there is no revolving chamber and no escape of gas at the breech. It gives stronger shooting than a revolver, but is more cumbrous, and has the serious defect that the shock of the discharge of one barrel sometimes prematurely fires a second barrel.
 |
| Figs. 7 and 8.—Colt double-action revolver. |
In 1865, Sharp, an American, patented an invention to remedy the escape of gas, in which the four barrels of the pistol were drilled the full length out of one block of metal. The barrels were slid forward by an under lever to load, and the firing was effected by a revolving head to the hammer, set by the action of cocking the pistol.
About 1878 Messrs Lancaster introduced both two- and four-barrelled hammerless pistols, in which an internal hammer was worked by the pull of the trigger. In all the three weapons
