such a position that the blank ammunition magazine only can be fed into the gun. (d) Magazine (blank ammunition).—The magazine for firing blank ammunition operates principally the same as the standard magazine. The loading tool provided with the Browning magazine will serve to load the blank ammunition from clips into the blank-ammunition magazine. The blank-ammunition magazine is made up by altering the standard Browning magazine and inserting the cartridge guide to guide the blank cartridge from the magazine and to block out service ammunition from the magazine. A V-slot is made in the left side of the magazine to allow clearance for the safety on the gas cylinder tube retaining pin. This gives additional safety by blocking out the service magazine, which would otherwise make it possible to load service ammunition into the gun. The standard service magazine follower is used with the changes noted. The magazine spring and base are the same as are used in the service magazine. The insertion of the magazine requires the least bit of training, as the lower part of the magazine must be tipped slightly to the left side of the gun to allow the safety to enter the slot of the magazine. This is made necessary in order to reinforce the magazine at the top of the V-slot. This could be eliminated by extending the slot to the edge of the magazine; however, this would have left it too weak. Should the magazine feed the cartridge too high to enter the chamber properly, a slight closing in of the lips of the magazine or a forcing down of the cartridge guide slightly will eliminate this malfunction.

(c) The following instructions will be strictly adhered to: Before inserting the blank ammunition in the automatic rifle first observe the cartridge to make sure that it is a blank cartridge. The space for the top cartridge will allow one service round of ammunition to be fed into the magazine. Two service cartridges can be fed into the blank ammunition magazine. However, when the bolt goes forward the two service cartridges bind against the cartridge guide, which prevents their feeding. When by accident a single round, top cartridge, is fed into the magazine it will feed, and every precaution must be taken to make sure the top cartridge in the magazine is a blank. (f) All magazines loaded with blanks must be inspected before inserting in the gun. The safety on the gas cylinder tube retaining pin will block out the service magazine, thereby making it safe against loading service ammunition in the gun.

7) With the Browning automatic rifle made ready for firing, remove the gas cylinder tube retaining pin, insert the gas cylinder tube retaining pin and safety assembly. Make sure the gun is not loaded, remove the flash hider, and screw the muzzle piece in position with the combination tool. Load the magazine in the ordinary manner except use blank ammunition, model of 1909. This will be packed in paper cartons marked "20 cal. .30 blank cartridges, model of 1909, for service rifles,

models of 1903 and 1917, automatic rifle with muzzle attachment and machine gun with muzzle attachment." To remove the blank ammunition attachments, remove the muzzle piece first and the gas cylinder tube retaining pin and safety assembly last. The blank ammunition attachments and the rifle after firing should be thoroughly cleaned with pure water, then with soda solution if available, then dried thoroughly and oiled. Ammonia solution need not be used after firing blank ammunition, as there is no metal fouling to be removed. In case water or soda solution is not immediately available after firing a thorough oiling of the parts will prevent corrosion until cleaning facilities are on hand.

11. To remove firing pin without stripping.-Lay the rifle on the table, barrel down, muzzle to the front. Remove trigger mechanism. Place rim of cartridge under bolt guide (Pl. 21a). Pull operating handle to rear and hold mechanism back. Steady the cartridge with the thumb and forefinger of the right hand (Pl. 21b). It may be necessary to exert a slight downward pressure on the nose of the cartridge in order to pull the bolt guide out far enough to free the bolt. Push down on bolt link, causing bolt to break at bolt lock pin (Pl. 21c). Allow mechanism to go forward until it stops. Replace firing pin. Then pull operating handle to rear again and push bolt into position (Pl. 21d).

12. To remove extractor without stripping.—Draw back mechanism and insert empty cartridge case between bolt and chamber, exposing the extractor (Pl. 22a). With the forefinger of the left hand, force out the claw of the extractor, then place point of cartridge behind the extractor shoulder and pry forward until extractor is free of recess (Pl. 22b). Remove extractor spring.

To assemble extractor, insert short end of extractor spring in hole in the shank of extractor, having the long end of the spring along the slot in the extractor. Insert extractor and spring in end of bolt and push into position (Pl. 22c).

13. Explanation of functioning.-All automatic weapons must have mechanical means for performing the following functions: Extraction, ejection, feeding, locking the breech while there is a high pressure in the bore, and igniting the cartridge.

Operations, such as extraction and ejection, are performed by various cams, lugs, and springs, and the energy necessary to perform this work and to overcome friction in the rifle is derived from the explosion of the powder in the chamber.

14. Detailed functioning.-a. The functioning of the Browning automatic rifle is divided into two phases based on the natural operations of the mecha