(_c_) Turn the screwdriver edgeways and insert it behind the horns of the extractor and between the face of the barrel and front of the lock flange, and force the lock to the rear. (_d_) Turn crank handle on to the buffer spring, press down the extractor, raise the lock and remove the live cartridge, then lift out the lock. (iv) =Damaged Parts of the Lock, no Spare Part being available.= The gun will fire without the sear, or if the bents of the sear or firing pin are badly worn or broken off, but only single shots, and only by pressing and releasing the double button quickly. The gun will also fire if the nose of the trigger or bent of the tumbler is badly worn or broken off, but only rapid firing. In this case the gun will fire the instant the crank handle reaches the check level, although the double button has not been pressed. The gun can be worked as follows:— (_a_) Group the cartridges in the belt, say 20 or 30 rounds each group. (_b_) Lay the gun before commencing to load, place crank handle on buffer spring, pull belt to left and let handle go; repeat, but before allowing the handle to reach check lever and the gun to fire, grip the rear crosspiece with left hand to control gun in the ordinary way. If necessary firing can be stopped by throwing the filled end of the belt over the breech casing to the left. When the firing has been stopped as described above, hold the crank handle with the right hand, open the cover, press down the horns of the extractor, draw the lock back, and, if there is a live cartridge on the face of the extractor, remove the feed block and belt, close the cover, and allow the lock to fly forward, when the live cartridge, which is on the face of the extractor, will be fired automatically. The lock can then be changed with safety. On no account should the lock be allowed to fly forward until the feed block has been removed and the cover shut. If, on drawing the lock back, it is found that there is no live cartridge on its face, the lock may be changed at once, and the necessity for removing the feed block and the subsequent precautions will not arise. (v) =Gunmetal Valve Working Loose.= This will prevent the barrel from going home. It may be temporarily remedied by tapping it round with a hammer and punch, but it should be tightened at the earliest opportunity with the gib key, the barrel being removed from the gun. ·303–inch Vickers Gun. Explanation of Plates IV and V. Similar numbers indicate corresponding parts in all the plates. 1. Casing, barrel. 2. Tube, steam. 3. Bracket, foresight. 4. Gland. 5. Casing, breech. 6. Cover, front. 7. Cover, rear. 8. Sight, tangent. 9. Bar, trigger. 10. Lock, rear cover. 11. Rear-crosspiece.