Hotchkiss Portable Machine Gun.

Plate X.Infantry Model with Elevating Gear.

Plate XI.External Parts.

Plate XII.Working Parts.

ACCESSORIES.

One dismounting wrench.One ejector key.One hand extractor.One cleaning rod complete.Two wire brushes.One cleaning brush.One gas cylinder cleaner.One oil can.One front sight cover.

One dismounting wrench.

One ejector key.

One hand extractor.

One cleaning rod complete.

Two wire brushes.

One cleaning brush.

One gas cylinder cleaner.

One oil can.

One front sight cover.

The gun comprises a single barrel, receiver, guard and stock, rigidly assembled. Guided in the receiver, parallel to and below the barrel, is the piston, which by its reciprocating motion assures the automatic action of the gun. This reciprocating motion is brought about as follows:—When the bullet in its passage through the bore has passed a port connecting the bore with the gas nozzle, a small portion of the powder gas issues from the nozzle, and impinging in the cup-shaped forward extremity of the piston, throws in the rear. The recoil spring compressed by the piston in its rearward movement now returns the piston to its initial position.

In its movement to the rear the piston, which is accompanied by the breech block, opens the breech, extracts and ejects the spent cartridge case, and brings a fresh cartridge to the loading position. In its forward movement the breech is locked and the shot fired.

The cartridges are fed into the gun on flat, tempered steel strips, of 30 rounds each.

A folding barrel restis provided for steadying the barrel when firing in the prone position which will ordinarily be taken.

For aircraftthe gun is mounted on a crutch, and the stock may be replaced by a pistol grip.

The operation of the gun requires but one man, who loads and fires. If a second operator loads the speed of fire is increased from 250 to 400 rounds per minute.

To load, the breech must be opened by means of the cocking handle. As the piston is drawn back, cams on its upper face turn the fermeture nut a partial revolution,disengaging its interrupted threads from corresponding threads on the nose of breech block. This unlocks the breech. Under the action of its spring, the feed piece engages with a shoulder on the piston and locks it in its rearmost position.

To permit the introduction of the feed strip, the feed piece must be lifted to its highest position by pressing up on its lower end. This frees it from the shoulder of the piston, which latter moves forward slightly under the action of its spring and engages with the sear. The feed strip may now be introduced into the guides, cartridge side down, and should be pushed forward until the pawl forming part of the feed spring engages with it, so as to prevent any backward movement.

When the trigger is pulled, the piston, accompanied by the breech block, is propelled forward by the recoil spring; the breech block pushes a cartridge from the feed strip into the chamber; the cams on the upper face of the piston act on the fermeture nut, locking the breech; the firing pin is driven against the primer and the shot fired.

When the bullet in its passage through the bore has passed the port leading to the gas nozzle, a small portion of the powder gas, conducted by the port and the gas nozzle, impinges in the cup-shaped forward extremity of the piston, and drives it to the rear. As already explained, the breech is now unlocked by the action of the piston cams on the fermeture nut, the breech block is withdrawn, along with the extractor holding the spent cartridge case, which later is ejected when its head strikes the ejector.

Towards the end of the backward stroke of the piston a cam on its side imparts a slight rotary movement to the feed piece, which advances the feed strip sufficiently to bring the following cartridge to the loading position.

The last cartridge having been fired, the strip is ejected from the gun. Under the action of its spring, the feed piece, which has been held up by the strip, now descends, and, engaging with the shoulder of the piston, locks the breech open. All is now ready for the introduction of another strip.

The firing gear may be set for continuous firing, single shots, or safety, by turning the cocking handle to the positions marked “A,” “R” and “S,” respectively.

When set at “A” (automatic), so long as the trigger is held back, the piston is free to move forward again under the action of the recoil spring. As a result the gun fires continuously until the strip is exhausted or the trigger released.

When set at “R” (repetition), a separate pull of the trigger is required for each shot, as the sear engages with the piston each time the latter recoils, thus stopping the firing.

When set at “S” (safety) the trigger is locked, and cannot be pulled back. As a result the gun cannot be fired.

1st.—Close breech.

2nd.—Remove cocking handle.

3rd.—Remove guard.

4th.—Withdraw recoil spring from receiver.

5th.—Remove recoiling mechanism.

6th.—Remove feed spring.

7th.—Remove feed piece.

8th.—Remove ejector.

9th.—Remove barrel.

10th.—Remove hand guard.

11th.—Unscrew and remove locking nut.

12th.—Remove fermeture nut.

13th.—Remove firing pin.

14th.—Remove extractor.

15th.—Remove firing gear from guard.

16th.—Remove cartridge stop.

1st.—Mount in order the following parts: fermeture nut, barrel nut, hand guard, barrel, ejector, spring and cap, feed piece, feed piece spring.

2nd.—Assemble the trigger, sear and sear spring, and then mount them in guard.

3rd.—Mount the recoiling parts in receiver.

4th.—Insert recoil spring in piston and push forward, allowing a few inches to project to rear of receiver.

5th.—Mount guard.

6th.—Mount cocking handle.

Replace defective part by a spare, and mount by reversing operations.

The extractor and extractor spring can also be removed without stripping gun as follows:—

Replace defective part by a spare, cock the gun and withdraw empty cartridge case.

POINTS TO BE ATTENDED TO BEFORE FIRING.

1. Cock gun.

2. Pass cleaning rod down the bore to make sure that barrel is clear.

3. See that regulators of all available barrels are properly set.

4. Oil mechanism. A moderate quantity of oil will suffice. It is useless to flood the mechanism. As the essential parts are sufficiently accessible through the ejection slot and by opening the feed piece cover, dismounting is not necessary.

5. Test action of both ejector and cartridge stop by pushing on their points. They should work freely, their springs being elastic but without stiffness.

6. Test action of mechanism by rapidly opening and closing breech several times. It should work freely and smoothly.

In firing, the prone position will be taken ordinarily, the barrel rest being used to steady the gun.

In high grass or under conditions where more height is desirable, ammunition boxes may be placed under the barrel rest so as to increase height.

In short, any sort of rest available may be used, for instance, the top of a parapet or the limb of a tree.

In going into action the following operations must be performed:—

(1) Set barrel rest.

(2) Mount elevating mechanism.

(3) Take firing position.

(4) Cock gun.

(5)Loadingis ordinarily performed by a second operator, who takes the prone position to the right of gun, with ammunition conveniently at hand.

N.B.—If gun is operated by but one man, loading will be found more convenient if the elevating mechanism is not used; the firer performs both operations of lifting the feed piece and introducing the strip with the right hand, the left hand meanwhile steadying the gun by grasping the stock.

(6)Firing.—The gun is fired by pulling the trigger.

N.B.—The trigger must be released at the end of each strip, so that the sear will hold the piston at the cocked position during the introduction of the following strip. Otherwise, as soon as the feed piece is raised preparatory to loading the breech will close, necessitating recocking the gun before continuous firing.

(7) Unloading.—In order to remove a partially spent strip, proceed as follows:—

N.B.—As a live cartridge never remains in the chamber the mere presence or absence of the strip shows whether the gun is loaded.

In prolonged firing it is sometimes desirable to replace a hot barrel by a fresh one, so as to allow the former to cool.

This operation, which is performed without dismounting any part of the mechanism, requires some 10 to 15 seconds.

Proceed as follows:—

Suppose the gun in the firing position.

The firer unscrews the locking nut one-sixth of a turn with the right hand, using the dismounting wrench.

While the second operator grasps the legs of the barrel rest, quite near the barrel, No. 1 separates the barrel from the receiver by drawing the latter to the rear.

Resting the butt on the ground No. 1 now mounts the fresh barrel and pushes it home.

Meanwhile No. 2 handles the hot barrel by means of the barrel rest, which he then detaches as follows:—

The fresh barrel being mounted, No. 2 attaches the barrel rest and resets it.

A hot barrel may be carried by means of dismounting wrench.

To reduce wear of rifling, the barrel should be kept cool if circumstances allow.

Water is not harmful, and when available may be copiously applied to barrel by means of a sponge or rag.

A hot barrel may be dipped in water, but all traces of latter must be removed from barrel bore and gas cylinder, by blowing through same, by means of cleaning rod, or by firing two or three loose cartridges.

Until all water is blown out of gas cylinder, the gas pressure may be insufficient for ensuring automatic action.

In order that the working of the gun may be regular, sufficient power must be available to ensure complete recoil of the piston. The amount of power necessary must vary because of insufficient oiling, dust, or fouling in the mechanism, &c. Then, again, pressure of the powder gases may vary because of temperature, deteriorated powder, or badly worn rifling.

The regulator affords means of varying the power which works the gun. Under normal conditions it should be set at 25.

To test the automatic action, fire several shots with regulator set at 25 and cocking handle at “R,” and observe:—

If these three points are not satisfactory it may be concluded that there is a lack of power, and regulator should be screwed up from 5 to 10 divisions.

On the other hand, too much power is not desirable, as the vibration due to the violent action of the mechanism necessarily affects accuracy.

In case of a jam always proceed as follows:—

(1)Jam on the first round of a strip.

The strip was probably not pushed completely home before trigger was pulled. Always push forward strip until pawl catches, so that both strip and cartridge are positively held in loading position.

(2)Missfire.

Eject defective cartridge by cocking gun, and continue firing.

N.B.—A loose primer falling into the mechanism may cause repeated missfires. Dismount the piston and breech block so as to remove primer, which will usually be found either in the piston cams or in the fermeture nut near the entrance to the chamber.

Missfires may be also due to a weakened recoil spring. In this case replace the spring with a spare.

(3)Bad introduction.

The cartridge jams at entrance to the chamber when being pushed forward by breech block. The bullet ofthe cartridge in question may have been imperfectly seated due to defective crimping, or the cartridge insufficiently held by the clips of the feed strip.

In the latter case the strip should be put aside for re-sizing.

Another cause of bad introduction is incomplete feeding due to lack of power. In this case screw up the regulator 3 to 10 divisions.

(4)Incomplete ejection of the spent cartridge case.

This is due to lack of power. Screw up the regulator 5 to 10 divisions.

This arm requires the same care as the service rifle. It must be kept clean and free from rust, and all parts lightly oiled. No gritty substances or emery should be used.

As soon after firing as practicable the barrel should be thoroughly cleaned and oiled, particular attention being paid to the chamber.

The gas cylinder should be kept free from fouling by means of the cleaner so that the regulator can be easily screwed up without using the dismounting wrench.

When the gun is not in use the breech should be kept closed so as to avoid weakening the recoil spring.

The feed strips hold 30 rounds each. There are three rows of clips which hold the cartridge near the base, the middle and at the neck. A stop lug which catches behind the head of the cartridge case prevents longitudinal motion.

The feed strip filling machine is constructed for clamping to a bench or plank, as, for instance, the lid of a cartridge box.

The hopper and clamp are removable for compactness in packing.

The machine must be so placed that the crank can be conveniently turned with the right hand.

Proceed as follows:—

This machine is operated most efficiently by two men. One supplies the machine with feed strips, turns the crank, and removes filled feed strips; the other supplies the hopper with cartridges.

N.B.—The feed strips may also be readily filled by hand; care should be taken that the rims of all cartridges bear back against their stop lugs.

When the feed strips have been used repeatedly, the middle clips sometimes lose their curvature to such an extent that the cartridges are not firmly held. This is quickly remedied by passing the strips through the re-sizing tool so as to restore the middle clips to their original form.

As a rule, very little re-sizing is necessary, slight contact between the re-sizing roller and the top of the middle clip sufficing.

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