8. Don’t full load the gun until signal is given.

 

9. Check bore for clean bore.  Covers or rags in the barrel have caused explosions while firing so be sure such things are removed before firing.  These projectiles are very sensitive.

 

10. In firing, the lock frame must be fully forward.  Recock, if it is not or cannot be pushed fully forward.  Do not pull lock frame to the rear except as a last resort.  Charging the gun is dangerous for normally the projectile will pull free from the casing.

 

11. The gun is easily maintained.  Cleaning and light oiling of the barrel and block are all the servicing required.

 

12. The U shaped connection should be facing up and the safety catch must be on the outboard side.

 

13. Lock the barrel correctly.

 

14. Left and right drive rods are not interchangeable.  Keep oil at the proper level in the recuperating cylinder, use only US Army Spec. No 2-36D.

 

15. Oil for cleaning can be either 211- or 2190.

 

16. Both AP and HE have tracer.  Good results have been had with a ratio of 1 AP and 3 HE.

 

40 mm Gun:  This gun is best operated with 4 men but 3 men can do a good job.  It is a wonderful gun for both AA and surface fire.  It seldom jams.  The prime point to remember is load the shells at the proper angle, nose canted downward.

 

20mm Gun:  This gun is so powerful that it has earned the name cannon.  When you hit something with a 20mm, you really do some damage.  Not small punctures but gaping holes are the marks left on the enemy by this powerful shell.  Aside from the usual preparation and care of a 20mm, the following are helpful hints:

 

1. Precaution must be taken in clearing a 20mm jam.  Always have a bucket of water on hand.  When a jam occurs, souse the breech and barrel.  If you cannot get the projectile out in a few seconds, secure the gun for about 5 minutes.  In any case, never stick your nose or fingers into the breech.  Keep clear and use your ram rod.

 

2. Practice cocking of the 20mm.  It is a tricky operation and should be done speedily and with easy, especially in the dark.  It is the only way to clear a jam, and to get the gun set to fire again.

 

3. The loader must get a rhythm in his task and eliminate groping at night.  The gunner and loader who drill in the daylight with their eyes closed are doing a wise thing.  The magazine is quite heavy.  On a high trunnion gun, the loader should be both strong and tall.