barrel, and in this part a channel or groove is made descending from the point b in both directions, so as to form two inclined planes meeting at the point b. These planes or sections of the grooves may form an angle at forty-five degrees with each other. This groove or channel serves as a chimney to conduct off the smoke of the lateral discharge, so that it shall pass directly between the receiver and the barrel and prevent its spreading, so as to pass in between the receiver and the arbor and the barrel and the arbor, and consequently from condensing there and rendering them foul. The barrel is connected with the receiver and with the stock of the gun by the aid of the arbor which at the rear end, is a solid piece with the shield or solid piece of metal which receives the recoil and constitutes a component part of the metallic frame-work or foundation of the lock and its appendages. The part C of the arbor is that upon which the receiver revolves, and the part C′ enters a cylindrical cavity in a mass of iron, D D, to which the barrel is brazed or otherwise attached.

Fig. 3 shows the piece of iron D D and a part of the barrel B which is attached to it. The dotted lines in this represent the cylindrical cavity which receives the outer end of the arbor C′. The two are keyed together by the passing of a suitable key through a mortise in the piece D D and a corresponding one in the arbor.

c, Figs. 1, 3, 4, and 5, represents the key. Fig. 4 shows its upper and Fig. 5 its under side, d d are two fluted channels along its upper side to receive the heads of two screws which are screwed into the piece D D close to the mortise and on the side opposite to that shown in Fig. 3. The heads of these screws lap a little over the mortise and are received into the fluted channels d d. These heads prevent the key from falling out and check it in either direction, and must be withdrawn in order to remove the key. As the key c is to act laterally as a wedge to draw the receiver and the barrel into proper contact, it is of importance that it should be checked when forced sufficiently far in, or the receiver might be wedged up and prevented from turning. For this purpose I insert a screw, e, Fig. 3, into the steel button f, which is attached to D D, to strengthen the end of the mortise and prevent the bruising of it by the recoil. The head of this screw, overlapping the end of the mortise, receives the wedge and checks it. By turning this screw the force of the wedge may be tempered. In Fig. 5, g is a spring-latch on the under side of the key, which catches upon D when the key is forced in and prevents its accidental removal.

Fig. 6 represents a percussion tube or nipple, through which the fire from the percussion-cap is to be conducted to the chamber. Fig. 7 represents the same in section. The outer end, h, of the tube has the opening made as large as convenience will allow, and it goes tapering or conical until at the inner end, i, it is as small as a proper entrance of the flame from the percussion-powder will warrant. By giving the conical or funnel-formed opening to the tube the effect of the percussion-powder is greatly increased.

E, Figs. 1 and 8, is a bolt for locking the receiver when a loaded chamber is brought to coincide with the barrel, the rounded end j being forced into a hole in the receiver by the action of a spring on its outer end k. This bolt is drawn back by the hammer F in the act of cocking.

l, Figs. 1 and 9, is a spring-cam, which is screwed to the hammer at m. It is made of spring-steel, so that its cam end n may recede from or approach the hammer F. The cam n bears against the projection o on the bolt E on the side which lies against the hammer, and as the hammer is drawn back causes the bolt to recede. The bolt is notched to enable it to be withdrawn without interfering with the joint-pin q