(_b_) The inner-case pin (Fig 56) engages a stop on the inside of the ignition cylinder. The five projecting metal matches on the inside of the ignition cylinder are each in turn stopped by the lug on the forward-facing surface of the ignition-head body. [Illustration: Fig 55. Ignition head disassembled, showing nomenclature and Chemical Warfare Service stock numbers for requisitioning spare parts.] When the trigger is pulled, the trigger rod pushes a match forward, causing an incendiary charge in the ignition cylinder to ignite. The spring in the case rotates the ignition cylinder until another match is stopped by the lug. [Illustration: Fig 56. Parts of ignition head and ignition cylinder.] (_c_) The outer-case pin (on the outside surface of the outer spring case) fits into the notch in the ignition shield and holds the spring case as the shield is screwed into position. This action winds the spring in the case. (_d_) A snap ring holds the spring case on the ignition-head body. (8) _Ignition shield_, a cylindrical, thin-metal tube with a conical front end. The shield guides the flame and protects the firer. Eight holes around the base of the cone provide an air intake for burning the fuel. The base of the shield is threaded, and it screws onto the ignition-head body. A notch (Fig 56) in the base of the shield receives the latch and the outer-case pin of the spring case. _b. Removal of ignition head._ To remove the ignition head, proceed as follows: (1) Remove shield by lifting latch and unscrewing shield counterclockwise. (Fig 14) Keep hands and face away from front of barrel. (2) If ignition cylinder has not been removed, remove it or allow it to fall off barrel. (3) Pry off snap ring which holds spring case in position, using screw driver. (Fig 57) Be careful not to damage or break the ignition-head body by applying too much leverage. (4) Remove the four screws and lock washers which hold ignition-head body and coverplate together. Lift off coverplate. (5) Trigger, trigger spring, trigger rod, latch, and latch spring may be removed. (6) Using a hex wrench, loosen set screws (Fig 58) and withdraw barrel from ignition head. _c. Installation of ignition head._ To install ignition head, proceed as follows: (1) Insert barrel in ignition-head body, pushing it as far forward as the shoulder on the barrel permits. (2) Aline front grip and valve grip. (3) Using hex wrench, tighten set screws on barrel enough to hold but not so tight that barrel is dented. (4) Place latch, latch spring, trigger and bearing, trigger rod, and trigger spring in position. (5) Put coverplate on ignition-head body and replace the four lock washers and screws. (6) Slip spring case over barrel, and lock by forcing snap ring into the groove.