[Lone Sentry: FM 17-76: Crew Drill and Service of the Piece, Medium Tank, M4 Series (105-mm Howitzer)]
[Lone Sentry: Photos, Articles, and Research on WWII]
Home Page  |  Site Map  |  What's New  |  Search  |  Contact Us

FM 17-76: Crew Drill and Service of the Piece, Medium Tank, M4 Series (105-mm Howitzer)
Field Manual, War Department, September 15, 1944
[DISCLAIMER: The following text is taken from a WWII U.S. War Department Field Manual. As with all field manuals, the text may be incomplete or inaccurate. No attempt has been made to update or correct the contents of the field manual. Any views or opinions expressed do not necessarily represent those of the website.]

Section V

13. GENERAL. a. The crew of the howitzer consists of the gunner, who aims and fires the piece; the cannoneer, who loads the piece; and the tank commander, who controls and adjusts fire.

b. Training in service of the piece must stress rapidity and precision of movement and teamwork.

14. POSITIONS OF HOWITZER CREW. Positions of the howitzer crew are as prescribed in paragraph 4b.

15. OPERATION OF HOWITZER. a. To open the breech. Grasp the breech operating handle and squeeze the latch until it is disengaged from its catch. Push the breech operating handle to the rear and right as far as it will go.

b. To load. Holding a round of ammunition with the right hand at the base of the cartridge case and the left hand at the middle of the assembled round, insert the nose of the projectile carefully into the chamber to avoid striking the fuze. Remove the left hand and with it grasp the operating handle. Clench the right fist, and thrust the round home into the chamber. As the rim of the cartridge case engages the extractor, it starts the closing motion of the breech block. When this motion is felt, close the breech by moving the operating handle to the left and forward with the left hand. Check to see that the latch locks the handle in the closed position. Move the body and both arms to the left clear of the path of recoil, and signal "Ready" by tapping the gunner's left leg with the foot.

c. To lay the piece. Bring the target into the field of the telescope by the quickest practicable method, under guidance of the tank commander or by use of the periscope. To lay for direction traverse until the center line of the telescope is on the center of the target or until the proper sight picture is obtained. Make the final traversing motion against the greatest resistance, such as might be caused by cant in the tank. Then move the piece until the target shows at the proper range indicated by its relation to the range lines of the reticle. Adjustment is calculated so as to depress the muzzle with the final motion. d. To fire the piece. Before firing, move the firing switch on the instrument panel to "ON". To fire, with the right heel depress the right hand firing switch button on the turret basket floor. If the piece fails to fire proceed as in paragraph 16. It may also be fired mechanically by depressing the firing pedal at the front edge of the basket floor.

e. Safety precautions. (1) Before loading each round, the piece will be inspected to see that there is no obstruction in the bore.

(2) The gunner must release the firing switch button of firing pedal after firing to avoid injury to the cannoneer.

(3) The gunner waits for the cannoneer's signal that the gun is loaded and he is clear of the recoil before operating the firing switch.

(4) After firing, during range and combat practice, the howitzer will be inspected by an officer to see that it is unloaded before the tank is moved or personnel is allowed to move in front of it.

(5) In loading the piece, care must be taken not to strike the fuze or primer of a shell against any solid object; after loading, the cannoneer must take care to remain clear of the path of recoil.

(6) Stuck rounds will be removed from the bore only with rammer, cleaning and unloading M5, or with the rammer M1, which are made for this particular purpose. The method of removing is given in g and h below.

(7) Ammunition will be cleaned and inspected before stowing and each round will again be inspected before loading.

(8) Fuzes will not be disassembled or tampered with in any way.

(9) In case of a misfire, the firing switch is immediately opened before recocking. Do not touch breech mechanism until the firing switch has been opened.

(10) See safety requirements of AR 750-10.

f. To unload an unfired round. The cannoneer cups his hands close behind the breech to catch the base of the round as it emerges and to prevent it from slipping out and dropping to the floor. The gunner opens the breech slowly. (Do not attempt to open, the breech rapidly, or the case may become separated from the projectile.) He then removes the round and returns it to its rack.

g. To remove a stuck projectile. If, in spite of care in opening the breech, the case and projectile do be come separated, the projectile is fired out whenever possible; this is especially true in combat where unnecessary exposure of personnel is to be avoided. If it must be removed without firing the piece, the chamber should be filled with rags to form a cushion, the breech closed, and the shell rammed loose as described in h below and removed.

h. To unload a stuck round. When a round is stuck in the piece and it is either impossible or inadvisable to fire it out, it will be removed, except in combat, under the direct supervision of an officer. The breech being open, the cannoneer takes position to receive the round as it is pushed from the chamber, while the bow gunner or gunner dismounts and rams the round out. Using the rammer, cleaning and unloading M5, insert it in the muzzle of the gun and push it gently down the bore until it is seated on the ogive of the projectile. Exerting a steady pressure, shove the round clear so that it may be removed by the cannoneer. If the weight of several men against the staff does not suffice (under no circumstances will the staff be used to hammer against the projectile), apply leverage by means of a 2" x 4" piece of wood or other suitable object connected to the tank by a rope at one end, or use the rammer M1, which provides a controlled and properly cushioned blow. Keep all parts of the body as clear as possible from the muzzle or breech during the operation. If this procedure fails to remove the round, experienced ordnance personnel should be called. In combat, to avoid exposing personnel to enemy fire, the round can sometimes be pried out by using the base of an empty shell case as a lever.

16. MALFUNCTIONS. Malfunctions of the howitzer may be divided into three general classes: failure to load, failure to fire, failure to extract. Below are given the causes of the principal types of failure and the immediate action remedy to be applied.

a. Failure to load.

 Failure   Cause  Immediate Action and Remedy
Round does not fully enter chamber. Stuck round. Remove round.
    Check for obstruction in chamber.
    Check for dirty round, and clean. Check for "bulged" (deformed) round. For removal of separated or stuck rounds see 15g and h above.
Breech does not close. Insufficient force in pushing round home, to clear breechblock. Withdraw round and try again.
  Bent or undersized case rim. Turn round so that rim engages extractors, or use new round.
  Obstruction, dirt or friction, in breech mechanism. Remove obstruction or dirt from recess if present; otherwise remove, disassemble, clean, and lubricate breechblock.
  Worn or broken extractor. Replace extractor.

b. Failure to fire.

 Failure   Cause  Immediate Action and Remedy
Piece does not return to battery. Obstruction between breech ring and rear portion of mount. Drive out obstruction, or, if necessary and jack is available, use tank jack between breech ring and shoulder guard bracket of mount, to release obstruction.
  Excessive friction of tube in cradle bearing. Relubricate. Take to ordnance if condition persists.
  Too much recoil oil. Remove excess oil.
If piece is in battery:    
Action of trigger mechanism restricted. Safety on "Safe". Move safety to "Fire".
Blow of firing pin fails to fire round. Defective round. Recock piece and attempt to fire a second time.
    Remove round to determine cause of misfire. (AR 750-10.) (See paragraph 15 for removal of live rounds.)
  Weak blow on primer due to: obstruction, dirt or friction in firing mechanism. Disassemble firing mechanism and remove obstruction or dirt, clean, relubricate, and assemble.
  Broken tip on firing pin. Replace firing pin.
  Broken or weak firing spring. Replace firing spring.
Firing pin fails to strike primer. Obstruction, dirt, or friction in firing mechanism. Disassemble, and remove obstruction, clean, lubricate.
  Weak or broken firing spring. Replace.
  Defective firing pin. Replace.
  Defective cocking lever. Replace.
  Defective cocking fork. Replace.
  Defective cocking lugs, on percussion mechanism. Replace mechanism.
  Defective sear. Replace.

c. Failure to extract.

 Failure   Cause  Immediate Action and Remedy
Breech opens, but case is not extracted. Broken extractor. Pry or ram out empty case and replace extractor.
  Undersized or bent rim. Pry or ram out.


[Back to Table of Contents] Back to Table of Contents