(7) If shield cannot be turned by hand tight enough to engage latch, unscrew shield. Then turn shield backwards until threads engage and repeat (6) above. [Illustration: Fig 14. Unscrewing ignition shield, with pressure on latch.] [Illustration: Fig 15. Placing ignition cylinder on gun. Care must be taken to avoid striking or pushing metal matches of cylinder.] [Illustration: Fig 16. Ignition cylinder in place on gun before replacement of ignition shield.] [Illustration: Fig 17. Ignition head assembled for firing of gun.] [Illustration: Fig 18. Tank group adjusted on firer.] 19. CARRYING THE TANK GROUP. The tanks are supported on the firer’s back and secured to it by two shoulder straps and two pairs of body straps. (Fig 18) The straps may be adjusted by the buckles to fit the operator. The shoulder straps pass over the shoulders and under the arm pits; the lower body straps are clasped tightly in front of the body; and the upper body straps are clasped across the chest to prevent the shoulder straps from slipping and the tank group from rolling off the back. Adjustments to the various straps should be made until the unit is carried with the bottom of the fuel tanks at the small of the operator’s back. The tank group should fit snugly so that it does not shift if the operator changes position quickly. 20. CARRYING THE GUN. [Illustration: Fig 19. Carrying the gun, with hands in position to fire.] The procedure for carrying the gun is as follows: _a._ Carry the gun with the hose at the right side. (Fig 19) _b._ Grasp the valve grip with the right hand and the front grip with the left hand, being careful not to operate the controls until ready to fire. _c._ Keep the gun pointed away from friendly personnel at all times. _d._ Do not face the front of the gun at any time. Even when no fuel is being ejected, the incendiary charges of the ignition cylinder can cause severe burns. _e._ Keep the gun dry and clean if possible. Avoid getting dirt or foreign matter into the weapon. _f._ Avoid rough handling. _g._ Wear gloves if available. _h._ Carry any extra ignition cylinders only in metal containers. 21. OPENING PRESSURE-TANK VALVE. The release of pressure into the fuel tank causes a hissing sound. Therefore, open the pressure-tank valve while still out of hearing range of the enemy. Do not, however, open it prematurely because of the possibility of pressure leaks. To prevent frothing of the fuel, keep the tank group in as nearly an upright position as possible when opening pressure-tank valve. Be sure to turn the valve handle all the way in a counterclockwise direction. Stiffening of the fuel hose occurs when the pressure-tank valve is opened. 22. RANGES. Firers and assistants should learn to judge ranges by frequent practice under varying conditions. The firers should be trained to approach as close as practicable to the target and to fire if possible at point-blank range for the greatest results. _a. Point-blank range._