(iii) =Use of Gauze.=--Grit must be removed from the gauze and pull-through before use. Cleaning with gauze entails wear of the bore of the rifle. Gauze should not be pulled through the barrel more often than three or four times without sufficient cause. The surest way of preventing the necessity for the continued use of gauze is to keep the bore well oiled so as to prevent rust. A barrel which has become rusty will always be more liable to rust than one which has been kept in good condition. It will therefore require more attention and more frequent cleaning with gauze. Similarly, a barrel in which erosion has commenced will require more care than one of which the surface has not been attacked, for, the eroded portion being rough, moisture is more likely to collect on it and form rust. It is also more difficult to remove rust thoroughly from a rough surface than from a smooth one. =4. Oil.=--No oil other than Russian petroleum should be allowed to remain in the bore. The function of this oil is to cover the bore with a waterproof film, and thus prevent moisture attacking the steel and forming rust. It must be well worked into the flannelette with the fingers, otherwise it will be scraped off by the breech end of the barrel. When paraffin has been used, all traces of it should be removed thoroughly, and the bore coated with Russian petroleum, for paraffin, though an efficient agent for removing rust, does not prevent its formation. =5. Caution.=--_No gritty or cutting material, such as emery powder or bath brick, is to be used for cleaning any part of the rifle._ Section =4=.--Instructions for Cleaning Arms. =1. To Remove the Bolt.=--Raise the knob as far as it will go, draw back the bolt-head to the resisting shoulder, and release it from the retaining spring. Raise the bolt-head as far as possible (in the short rifle, Marks I, I*, II, and II*, draw back the charger guide, then turn the bolt-head to the left), and remove the bolt. =2. To Replace the Bolt.=--(i) See that the resisting lug and cocking-piece are in a straight line, and the bolt-head screwed home. Place the bolt in the body with the extractor upwards, and press it forward until the head is clear of the resisting shoulder (in the short rifle, Marks I, I*, II, and II*, turn the head to the right, then push the charger guide forward as far as possible). Turn the head downwards until it is caught by the retaining spring. Close the breech, and press the trigger. (ii) In some rifles, the bolt can be replaced and closed with the bolt-head unscrewed a whole turn. It cannot, however, be closed with the bolt-head in this position if there is a cartridge in the chamber. The greatest care should therefore be taken to see that the bolt-head is screwed fully home before the bolt is placed in the rifle.