Rotary Chamber Mechanisms

with the barrel. Thus, each time a chamber is brought into position behind the barrel, the gun tube is completed and the weapon is in readiness for firing. This arrangement has the advantage of permitting repetitive fire without the necessity for having the weight and bulk of a large number of complete barrels. As mentioned previously in this chapter, this idea was conceived at a very early date in the history of firearms and, in fact, one of the first patented manually operated revolving type machine guns employed the multiple chamber principle. This remarkable weapon, invented in 1718 by James Puckle of England, had a number of separate explosion chambers which could be preloaded and were mounted in a circular array so that they could be successively revolved into alignment with a single barrel. The rotation was accomplished by means of a hand crank and the propellant charges were ignited by the slow-match method.

Over the years, the same general idea of having a single barrel with a number of explosion chambers appeared in a multitude of forms. In many cases, the individual explosion chambers were all bored into a single cylinder in a mannersimilar to that employed in the typical modern revolver hand gun. This arrangement, which is simple, easily mechanized, and effective, has been so prevalently used that in the popular mind it has become practically synonymous with the idea of the multiple chamber weapon. However, it should be realized that the revolving cylinder mechanism represents but one of the many possible devices which can be tised to make use of many chambers. It may be said that the archetype of the multiple chambcr weapon is found in a machine gun developed irt the United States near the middle of the nineteenth century-. This highly interesting weapon, the Ager "Coffee Mill" gun, which was used by the Union forces during the Civil War, was designed so that each charge of powder and ball was loaded into a separate steel container. The steel container forms the explosion chamber for the round and a pcrcussion cap is placed on a nipple screwed into the rear end of the container. In the operation of the gun, a number of loaded containers (explosion chambers) arc placcd in a hopper at the top of the gun and when the operating hand crank is turned, one explosion chamber at a time rolls down into a recess at the rear of the gun barrel. The gun shown in fig. 4-2 is a simplified version of this type of weapon. A system of cogged rollers operated by the hand crank guides the explosion chamber into place and allows the chamber to be shoved forward to form a prolongation of the barrel and to be locked from behind by a wedge. As the hand crank is turned, the round is fired and the rotation of the cogged rollers causcs the empty chamber to be ejected from the weapon at the side. As the fired chamber is ejected, a loaded chamber is brought into place to start a new cycle of operation.

Another unique arrangement for handling explosion chambers which are separate from the barrel is found in a hand gun developed later in the nineteenth century. Although the mechanism happened to be applied in a small calibcr, the same device could have been used just as easily in a larger weapon. This gun, which has the surprisingly large capacity of 20 shots, fires cartridge ammunition and has an individual chamber for each cartridge. The separate chambers are linked together with metal plates so as to form an endless loop similar in appearance to an ordinary bicycle chain as shown in fig. 4-3. As the gun is fired, a ratchet-type cylinder within the frame pulls the chain of chambers through the frame laterally in such a way as to bring the chambers successively into alignment with the barrel. Before each cartridge is fired, the gun mechanism securely locks the chamber in place. Of course, one of the prime requirements for a hand gun is that it be compact and easy to handle. It is relatively easy to imagine what embarrassment might be experienced by a man who, in defense of his person, is required to extract from his pocket a gun with a foot or so of loose chain attached. Nevertheless, although the gun no doubt does not represent the most convenient hand arm, the basic idea is sound from the mechanical viewpoint and might even have proved to be useful in a machine gun. At any rate, it serves to demonstrate that very few stones were left unturned in the search for the ideal form of the multiple chamber mechanism.

From the preceding discussion of the type of multiple chamber weapon in which the explosion chambers are separate from the barrel, it is apparent that the basic consideration is that the chambers must be preloaded and then successively moved into place behind the barrel in order to complete the gun tube. For the present, the particular mechanism used to position the chambcr, whether this be a rotary action cylinder or some other device, need not be considered and primary attention will

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