Fitting of the attachment
- Barrel, Mark 2, drill purposes, blank.
- Cone, front, muzzle attachment, blank.
- Nut, adjusting, muzzle attachment, blank.
- Screw, adjusting, muzzle attachment, blank.
- Spanner, muzzle attachment, blank.
2. The barrel is specially choked at the breech and is marked ” DPB ” on the trunnion block. The adjusting screw is screwed into the front cone from the rear, so that its large end may engage in the muzzle cup. The front cone with the adjusting screw assembles into the outer casing of the muzzle attachment in place of the existing front cone. The adjusting nut screws on to the projecting end of the adjusting screw and locks against the face of the front cone. The spanner is suitably arranged for the muzzle cap, adjusting screw and nut.
Adjustment of the gun
3. The weight of the recoiling portions should not exceed 2 lb. The weight of the fusee should be about 4½ lb.
The adjusting screw of the muzzle attachment should first be screwed inwards to the muzzle cup until it just begins to force the recoiling portions backwards. It should then be screwed 1¾ turns and secured in position by the nut. The screw may require further adjustment in order to obtain correct functioning, but in no case should the screw be less than 1 turn back from the muzzle cup. Adjustment should be made in ¼ turns.
4. Service guns will be used for firing. A belt, preferably as regards size of pockets part worn, should be employed. The blank ammunition should be inserted crimped and flush with the front edge of the belt, in groups of 10 rounds. This number is sufficient for the purpose of representing machine gun fire and ensures a longer life of choke in the barrel. The barrel casing will be filled as for ball ammunition. When firing becomes noticeably irregular, the barrel will be set aside for examination by an armourer.
5. On completion of blank firing, the guns will be immediately restored to their normal condition for firing ball ammunition. The gun will be cleaned in the normal way, (ie, as if ball ammunition had been used) except that no attempt will be made to clean the inside of the barrel forward of the choke.