The piece of tubing for The Barrel must be free from corrosion on the inside, it must be straight, and its ends must be reamed out with a file if burrs remain on the inside edges from the cutting of the pipe. The author used a piece of iron gas-pipe in his first model, but found that brass tubing is better as it presents a smoother inside surface, it is easier to cut, also. You can get brass tubing at almost any machine-shop. If they haven't a piece of the right size at hand, they will likely get a piece for you, or be able to tell you where you can get it. A piece 20 inches long is required. Figures 417 and 418 show how the chamber end of the barrel must be slotted for a length of 2 inches, and how the upper half of the tubing must be cut away for a distance of 4 inches. You can cut the slot with a flat file 1/8 inch thick, using it edgewise, and making the slot equal in width to the thickness of the file. The upper part of the tubing can be cut away by using the file flatwise. The pair of small holes shown pierced through the tubing near its end are provided for anchoring the barrel in the gun-stock by driving a finishing-nail through the gun-stock and through the holes.
The Front Sight (Z, Fig. 410) is a strip of tin of the size shown in Fig. 419, bent to fit over the muzzle of the barrel, with the tip of one end of the strip hammered over on to the other end (Fig. 420).
The wire for The Hammer Rod (G, Figs. 411 and 412) must be of No. 6 gauge. Figures 421 and 422 show the correct shape and size. To make the turns at the point for pivoting, bend the wire around a bolt or dowel-stick. Spools H
Figs. 417 and 418. - Details of Tubing for Machine-Gun Barrel Figs. 419 and 420. - Details of Front Sight
(Fig. 421) are used to keep the rod centered half way between sides D of the gun-stock frame. Cut off as much of the end of each spool as is necessary to make the pair of the right length to fill the space each side of the rod. A 1/4-inch bolt 3 inches in length is required for the hammer-rod pivot (I, Fig. 421).
The Hammer Spring is a screen-door spring (J, Figs. 411 and 421). Pull out several turns of one end as shown in Fig. 421, and slip them over the upper end of the hammer-rod. Pin the other end of the spring between pieces D with the nail K (Figs. 410 and 411), slipping the nail through the holes in the fore end of pieces D. It may be necessary to break off an inch or so of one end of the spring, to make it short enough so it will be held in tension when its ends are fastened.
The Firing Crank (L, Figs. 410 and 411) is made of wire of the same thickness as that used for the hammer-rod.
Figs. 421 and 422. - Details of Hammer-Rod and Pivot Fig. 423. - Detail of Firing-Crank
Figure 423 shows dimensions for bending the piece. The loop bent in this piece of wire acts as a tripper on the hammer-rod end, as you will see by looking at Figs. 410 and 411. The hammer-rod, spring, and firing-crank must be mounted in the gun-stock frame between side pieces D before the
Fig. 424. - Detail of Cartridge
Fig. 425. - Magazine Filled with Cartridges
Figs. 426 and 427. - Details of Magazine
FlG. 428. - Weight for Holding Cartridges in Position latter are fastened to the stock. Figure 411 shows the right position for the hammer tip when the hammer-rod has been released, and Fig. 412 shows the point to which the hammer must be drawn by the firing-crank rod tripper before being released. If you have bent the hammer-rod and firing-crank rod as shown in the drawings, the hammer tip should come at the two points shown. If it does not, bending the wires at slightly different angles will bring about the proper adjustment.
Before proceeding further with the construction, it will be well to test out the machine-gun with
Cartridges. These are pieces of dowel-sticks 3/8 inch in diameter, cut to the length shown in Fig. 424, with one end whittled cartridge-shape. Sandpaper the cartridges smooth, then wax and polish them. To make the bore of the barrel as smooth as possible, pour oil into it, and then, with a piece of soft rag on the end of a slender stick, spread the oil and remove the surplus. Give plenty of time to testing the firing efficiency of the gun, and adjust and readjust the hammer-rod and firing-crank rod until you are satisfied with the results obtained.
The Magazine (Fig. 425) is fastened to the gun-stock directly over the upper mortise, so that the cartridges dropped into it will slip into the chamber beneath. Figure 426 shows how to cut the piece of tin required for the magazine, from the side of a tin can. Leave the turned-over edge on the can side, as shown, to reinforce the upper edge of the magazine. Figure 427 gives the dimensions for cutting and folding the piece of tin. Bend the lower edge to form flanges through which to drive tacks for fastening the magazine to the top of the gun-stock.
The weight shown in Fig. 428 is necessary to hold down the cartridges so the bottom cartridge will always be in
Fig. 429. - Machine-Gun Tripod
Figs. 430-434. - Details of Tripod
Figs. 435-437. - Details of Yoke for Mounting Gun on Tripod the right position in the chamber for the hammer to strike. A piece of solder, or a piece of almost any kind of metal, will do. If you use solder, a screw-eye can be set into one side, to which to attach a piece of string as a means for lifting out the weight after the last of the cartridges has been fired, preparatory to refilling (Fig. 425). The slot in the side of the magazine is made wide enough so the finger can be slipped along it to guide the cartridges dropped into the magazine.
Figure 410 shows
The Tripod mount for the machine-gun, and Figs. 429 to 434 show details of its construction. Prepare the head block P of the dimensions given in Fig. 430, and cut three notches in the edge, of the sizes shown, and spaced equi-distantly, for the legs. Bore the center hole to receive the yoke spindle V (Fig. 436). Cut the front pair of legs R and the rear leg S of the sizes shown in Fig. 431. Bore a 24-inch hole through each leg 1 1/4 inches from the upper end, and cut off the corners of the lower end as shown. To mount the legs, screw a screw-eye into the tripod head each side of each notch (T, Fig. 432), then cut the dowel-pin pivots U (Fig. 433), and drive them through screw-eyes T and through the holes in the legs (Fig. 429). Cut socket block Q of the size shown in Fig. 434, bore a hole through its center to receive the yoke V, and fasten it to the exact center of tripod head P.
Prepare yoke V and lever W (Fig. 435) of the dimensions shown in Figs. 436 and 437. Cut the spindle on the lower end of yoke V to fit the hole in socket block Q, and bore a hole through the upper end of the yoke through which to drive the axis bolt for pivoting the gun, to provide for
Fig. 438. - Wash-Basin Helmet Figs. 439-441. - How to Attach Rings and Straps to Wash-Basin changing elevations. Use the thumb-bolt X and wing-bolt F(Fig. 410) for making this connection.
Paint all parts of the gun black or grey. To make them less conspicuous in the field, it is common practice to paint guns by what is known as the "rainbow smudge" system. But you will not want to dabble in the art of camouflage when finishing yourtoy machine gun.
To be an up-to-date machine gunner, you must wear
A Helmet like that the boys in Fig. 409 are wearing. A detail of this helmet is shown in Fig. 438. It consists of a tin wash-basin 11 inches in diameter (Fig. 439) with a pair of rings bent out of wire (Fig. 440) soldered to the inside, through which to run the chin-strap (Fig. 441). Stitch the strap to the rings, to keep the basin from slipping sidewise.