The following safety precautions were issued, in accordance with article 0406, Navy Regulations, by the Chief of the Bureau of Ordnance, 29 October 1948, and approved by the Acting Secretary of the Navy 3 November 1948. In separate publication, they are designated NavOrd Instruction 5100.1; and the contents are the same as the contents of chapter 20, U. S. Navy Safety Precautions, OpNav 34P1.

I. General

1. To avoid danger of casualties, the observance of the following safety precautions is mandatory. The Bureau of Ordnance shall be informed of any circumstances which conflict with these safety precautions or which for any other reason require changes in or additions to them.

2. When in doubt as to the exact meaning of a safety precaution, an interpretation shall be requested from the Bureau of Ordnance. Conditions not covered by these safety precautions may arise which, in the opinion of the commanding officer, may render further operation of the equipment unsafe. Under these conditions, nothing in these safety precautions shall be construed as authorizing such further operation.

3. Safety devices provided shall always be used as designated to prevent possibility of accident, and shall be kept in good order and operative at all times. All instructions promulgated by competent authority to insure safe operation or handling of equipment shall be strictly observed.

4. Whenever any motion of power-driven units is capable of inflicting injury on personnel or material not continuously visible to the person controlling such motion, the officer or petty officer who authorizes the unit to be moved by power shall, except at general quarters, insure that a safety watch is maintained in areas where such injury is possible both outside and inside the unit, and shall have telephone or other effective voice communication established and maintained between the station controlling the unit and the safety watch. These precautions are applicable to turrets, gun mounts, guns, directors, range finders, searchlights, torpedo tubes, rocket launchers, and similar units. Under the conditions stated above, the station controlling shall obtain a report “all clear” from each safety watch before starting the unit. Each safety watch shall keep his assigned area clear and if unable to do so shall immediately report his unit fouled, and the controlling station shall promptly stop the unit until it is again reported clear.

5. In turrets and enclosed mounts, a warning signal shall be installed outside the turret or mount; and whenever power train is used, except at general quarters, the officer or petty officer in charge of the turret or mount shall cause warning signals to be sounded before using power and at intervals during its use.

6. Changes, modifications in, or additions to ordnance material, or other material used in connection therewith, shall not be made without explicit authority from the bureaus concerned.

7. No ammunition or explosive assembly shall be used in any gun or appliance for which it is not designated.

8. No other than drill ammunition shall be used for drill.

9. On guns equipped with hydropneumatic counter-recoil systems, the safety link, locking the gun to the slide, shall be connected up at all times except when firing or when testing and overhauling the counter-recoil systems or when a battery is in a condition of readiness for action.

10. Except in action or when specifically authorized, antiaircraft guns shall not be fired at elevations greater than, or fuze settings less than, those prescribed in the current orders for Gunnery Exercises. When firing antiaircraft guns as such, all personnel not required to be exposed shall be kept under cover.

II. Ammunition Handling and Stowage

1. As familiarity with any work, no matter how dangerous, is apt to lead to carelessness, all persons who may supervise or perform work in connection with the inspection, care, preparation, use, or handling of ammunition or explosives- -.

(a) Shall exercise the utmost care that all regulations and instructions are rigidly observed.

(b) Shall carefully supervise those under them and frequently warn them of the necessity of using the utmost precaution in the performance of their work. No relaxation of vigilance shall ever be permitted.

2. Except in case of emergency, ammunition shall not be transferred during fueling operations.

3. All ammunition, explosives, and powder shall be protected from abnormally high temperature. If so exposed, they shall be handled in accordance with current instructions of the Bureau of Ordnance. Permissible maximum storage temperatures shall be prescribed by the Bureau of Ordnance.

4. Smokeless powder which has been wet from any cause whatever must be regarded as dangerous for dry storage. Such powder shall be handled in accordance with current instructions of the Bureau of Ordnance.

5. Smokeless powder which shows unmistakable signs of advanced decomposition shall be disposed of in accordance with current instructions of the Bureau of Ordnance.

6. To minimize the risk of fire, explosion, and damage to ammunition and its containers from accidental causes, ammunition shall be handled as little as practicable. As the action of denting thin-cased high-explosive ammunition is known to have caused detonation of the explosive in some instances, special care shall be exercised to insure that such ammunition is never struck, dropped, or bumped.

7. Defective bomb-type and thin-case ammunition shall be disposed of in accordance with current instructions of the Bureau of Ordnance.

8. A fuzed projectile, whether in a container or not, if dropped from a height exceeding 5 feet shall be dumped overboard in a manner conforming with regulations for dumping ammunition at sea except when practicable to turn the projectile in to a Naval Ammunition Depot. Such ammunition shall be handled with the greatest care.

9. Care must be used to avoid tapping or otherwise striking fuzed projectiles. This precaution is particularly applicable to attempts to loosen such a projectile in the cartridge case by repeated light blows of a mallet, unloading such a projectile wedged in the bore of a gun, and the striking of a projectile by the recoil of a gun or an ejected case.

10. The covers of switches, circuit breakers, etc., shall be kept securely closed while powder is exposed in the vicinity.

11. Magazines shall be kept scrupulously clean and dry at all times. Nothing shall be stored in magazines except explosives, containers, and authorized magazine equipment. Particular attention shall be paid that no oily rags, waste, or other foreign materials susceptible to spontaneous combustion are stored in them.

12. Naked lights, matches, or other flame-producing apparatus shall never be taken into magazines or other spaces used primarily as magazines while these compartments contain explosives.

13. Before performing any work which may cause either an abnormally high temperature or an intense local heat in a magazine or other compartment used primarily as a magazine, all explosives shall be removed to safe storage until normal conditions have been restored.

14. Black powder is one of the most dangerous of explosives and shall always be kept by itself. Only such quantities as will meet immediate needs shall be taken from the magazines. A container of black powder shall never be opened in a magazine nor in the vicinity of a container in which there is any explosive.

15. Ammunition shall not be altered, nor shall fuzes or any other parts be removed or disassembled, without explicit instructions from the Bureau of Ordnance.

Ill. Service of Guns, including Ammunition Supply

1. Live ammunition shall be loaded into guns for firing purposes only. Test or inspection of ammunition by fitting it into guns is prohibited, except when authorized by specific instructions of the Bureau of Ordnance.

2. During firing no other ammunition than that immediately required shall be permitted to remain outside of the magazine.

3. During gunnery exercises, charges in excess of the amount required to be available for one run shall not be assembled in the vicinity of guns mounted outside of turrets. No charge for a bag gun shall be removed from its tank, nor shall the tops of tanks be removed or so loosened that the bags may be exposed to flame until immediately before the charge is required for loading.

4. When either cartridges or bag charges are outside the magazines, each flame-proof compartment or space which forms a stage of the ammunition train, including the magazines and gun compartments (in or out of turrets), shall, wherever practicable, be kept closed from all other compartments or spaces except when the actual passage of ammunition requires it to be open. Where practicable, no flameproof stage of the ammunition train shall be open to both the preceding and the following stages at the same time.

5. If flame seals be damaged during firing, except in action, so that they can not fulfill their purpose, the gun or guns concerned shall cease firing until the flame seals are again effective.

6. (a) In a magazine or handling room in which powder is removed from tanks to be sent to the guns in bags, not more than one charge per gun, for the guns being served by that magazine or handling room, shall be exposed by removal from tanks, by removal of tank tops, or by so loosening the tank tops that the bags may be exposed to flame.

(b) In each subsequent flameproof stage of the ammunition train, not more than one charge per gun, for the guns being supplied through that stage, shall be allowed to accumulate. For this purpose, the spaces or handling rooms at the tops and bottoms of continuous-chain powder hoists will be considered separate stages (whether or not separated from the hoists by flameproof doors, flaps, or shutters).

(c) In addition to the above, continuous-chain powder hoists may be kept filled; or if hand passing is used, there may be one bag of powder at the station of each man in the train.

(d) It is the intent of this article to permit sufficient powder to be exposed to provide an adequate supply for the guns being served. The maximum amount specified above should be exposed only if a smaller amount will not assure an adequate supply.

7. As there is an inflammable gas present in the chamber of a gun after firing which, under certain conditions, may constitute a danger by igniting the powder charge which is to be used for the next round, and as smoldering remnants of powder bag may also be present, the following precautions shall always be observed:

(a) Bag guns shall not be loaded until a member of the crew has assured himself that the bore is clear of powder gases and remnants and has announced “bore clear” either by voice or by approved signal, such as a hand, whistle, gong, or horn, except that, when the gas-ejector system does not readily clear the bore, the combined sponge and rammer (where provided) may be used. The sponge shall be dipped in water for each load.

(b) Until the “bore clear” signal above described is given, or the projectile is rammed home with the wet combined sponge and rammer, powder shall not be exposed closer than 4 feet to a gun not mounted in a turret.

(c) In turrets fitted with ammunition cars, the car and the center of an open breach shall not be allowed within 6 feet of one another until the “bore clear” signal has been given. In turrets fitted with
continuous-chain powder hoists, or for hand passing, the powder shall not be exposed in the turret chamber, nor shall the flame seal, shutter, or flap between the turret chamber and the next stage in the powder train be opened or unlocked until the “bore clear” signal is given.

8. If a powder bag is broken to the extent of allowing powder to fall out, the command “Silence” shall be given and the loose powder shall be gathered up. If it is impracticable to utilize this section of the charge satisfactorily in loading, it shall be secured in a flameproof container or immersed in water.

9. In turrets not fitted with bulkheads between guns, the “bore clear” signal to the turret crew shall not be given until the guns which have been fired and whose breech plugs have been opened are reported clear, at which time one signal to the entire turret crew shall be given.

10. Care shall be exercised to prevent projectiles from slipping back from their seats, as unseated projectiles may cause abnormally high pressure. In bag guns, projectiles shall not be rammed by interposing one or more sections of a powder charge between the head of the rammer and base of the projectile.

11. The mushroom of every bag gun shall be wiped after each shot with a sponge or cloth dampened with fresh water.
12. As soon as a gun is loaded the breech shall be closed without delay.

13. When priming a lock of the sliding-wedge type, care shall be taken to insure the primer being pushed in beyond the primer catch to prevent the primer coming out or being crushed by the operation of the wedge in closing.

14. In loading a bag gun, neither the gun ready light switch nor the gun firing cut-out switch (which are combined in some installations) shall be in the closed position until the breech is fully closed and all personnel are clear of the recoil.

15. To guard against blowing out primers which may fire at the instant of closure, care shall be taken whenever the breech of a bag gun with a live primer in the lock is being closed, that the operating lever is followed through during the last part of its travel, to prevent any opening of the lock due to rebound.

16. The breech plug of a bag gun shall never be unlocked or opened while there is a live primer in the lock.

17. A firing lock into which a live primer has been inserted shall never be opened, either independently or by operation of the breech mechanism, unless the firing circuit is broken externally of the lock or breech mechanism (for example, at local pointer’s key or gun captain’s ready switch), except when it is known that the loaded gun has fired. This applies to the firing of primers at drill, to the operation of loaded guns, and the examination of primers.

18. The limiting position of the breech of the gun on recoil shall be indicated and the gun crew shall be instructed to keep clear.

19. While a gun is being unloaded, all personnel not required for the unloading operation shall be kept at a safe distance from the gun.

20. Only approved ramming devices and methods shall be used in loading live cartridges. Any cartridge which does not freely and fully enter the chamber of the gun shall be carefully extracted and put aside, and no further attempt shall be made to fire such a cartridge.

21. In every case gun using primers with a percussion element, except those guns of the sliding-wedge type, the breech plug shall not be closed until the plug-man is assured by actually feeling that the front face of the plug is free from any projections, such as a protruding firing pin or fuzed metal, in order to prevent discharge of the gun when the breech plug is swung to but not rotated.

22. In order to avoid danger from inflammable gases, fired cartridge cases shall, before stowing below, remain in freely circulating open air for at least 10 minutes. If practicable they should be stored on their bases.

23. Effective measures shall be taken to guard against prematurely opening the breech of a loaded gun, whether or not the gun is fitted with a salvo latch.

24. If a gun is loaded at the order “cease firing”-

(a) The gun shall be kept pointed and trained in a safe direction.

(b) The breech mechanism shall be kept fully closed.

(c) The gun shall normally be cleared by firing as soon as practicable.

25. A loaded and fuzed projectile, seated in the bore of a gun that is hot from previous firing, presents a hazard, since detonation of the projectile is possible as a result of being heated. Whenever practicable, such projectile should be disposed of promptly by firing the round. Whether a gun is hot or cold, the risks attendant upon removing a loaded and fuzed projectile seated in the bore, by backing out, are considered unwarranted except in the case of guns for which existing instructions specifically prescribe this procedure.

26. (a) The possibility of a serious accident due to opening the breech of a gun too soon in the case of a hangfire demands the constant exercise of the utmost prudence and caution. A hangfire must be assumed to exist when:

(1) An unsuccessful attempt has been made to fire the gun.

(2) A charge remains in a bag gun, with the possibility of ignition by an undetected ember from the previous round.

(b) The following procedure shall be followed in the cases noted above:

(1) Keep the gun pointed and trained in a safe direction.

(2) Keep the breech mechanism fully closed.

(3) Continue attempts to fire, if desired, repriming bag guns provided such efforts do not involve any movement tending to open the breech.

(c) If the gun is not fired under the above conditions

(1) Open the firing key and break the firing circuit elsewhere.

(2) Unhook the firing lanyard, if detachable.

(3) Remove the primer from the lock of a bag gun, using the primer tools supplied for this purpose, taking care to avoid danger from recoil or blowback. For this purpose, or for shifting primers, do not leave the firing lock open longer than necessary.

(4) Do not open the breech for 30 minutes (10 minutes for field and landing guns on shore) after the last attempt to fire. This, at the discretion of the commanding officer, is not obligatory in time of action; nor is it obligatory or advisable with a hot gun if an instruction of the Bureau of Ordnance to prevent a projectile “cook-off” recommends earlier opening of the breech when the gun cannot otherwise be cleared by firing it.

(d) The crew shall never leave a loaded gun until the precautions in (b) and (c) (1) to (3) above have been carried out.

(e) Ammunition removed from a loaded gun shall be disposed of in accordance with current instructions of the Bureau of Ordnance.

27. Ships shall cease the firing of any gun whose line of fire is endangering any object other than the designated target. These objects include friendly ships and aircraft and own ship’s structure together with the mounts and launchers and their barrels, fixed or moving. This stipulation applies to objects in the vicinity of the firing point, throughout the trajectory and in the vicinity of the target. Turrets, mounts, guns and launchers which are not firing, shall be trained and elevated if manned, or secured if unmanned, in a manner that will provide the greatest amount of safety from the firing. The position of greatest amount of safety of the unmanned mounts will generally be that position which the firing cut-out mechanism cams of the firing mounts were cut to clear.

IV. Precautions to be Observed in Handling, Fuzing, or Inserting Detonators in Explosive Ordnance

1. Since it is not always possible to ascertain readily whether mines, depth charges, rockets, projector charges, and aircraft bombs have been inadvertently armed in storage or handling, all of these types, when fuzed or assembled with firing mechanisms, shall at all times be handled and treated as if armed, in strict conformity with the instructions for safeguarding against the inadvertent arming, firing, or launching of such ammunition.

2. Certain types of bombs, mines, depth charges, rockets, and projector charges are normally issued unfuzed. Fuzes shall not be inserted in such ammunition (nor in the case of fuzes having separate detonators, shall the detonators be inserted into the fuzes) until just prior to placing in ready stowage, or just prior to or after loading the ammunition on the racks, launchers, or projectors preparatory to dropping or launching. Such fuzing or inserting of detonators shall not be accomplished in or near a magazine or ready service stowage, but may be accomplished in handling rooms or spaces specially designated for such purposes by competent authority. In general, fuzing or inserting of detonators shall be done on individual rounds isolated from other ammunition insofar as practicable.

3. Fuzes which have been set shall be reset to the safe position before sending them below.

4. Fuzes, firing mechanisms, or primer mechanisms for bombs, depth charges, rockets, projector charges, demolition outfits, or mines shall not, except as covered by special orders or current instructions of the Bureau of Ordnance, be removed, disassembled, repaired, or in any way altered.

5. Bombs, rocket heads, and projector charges, for which fuzes are issued separately, shall not be stowed with those fuzes installed in or near magazines containing explosives.

6. Fuzes issued separately for bombs, rockets, and projector charges, which contain integral detonators or other explosive components, shall be stored only in specially designated fuze magazines which shall not be located adjacent to magazines containing high explosives.

7. Detonators which are not assembled integrally with fuzes shall be stored only in standard type detonator lockers located in approved places.

8. Fuze-arming wires or devices shall not be removed from the unarmed position until just before releasing or firing. Safety pins or other devices requiring removal before flight, or firing, shall not be removed until the ammunition has been loaded in racks, projectors, or launchers and not until after the arming wire or device has been put in place. Bombs, mines, depth charges, rockets, or projector charges not expended shall be made “safe” at the first opportunity in accordance with current instructions for the respective assemblies. When handling or unarming an accidentally armed fuze, the prescribed procedure shall be carefully followed.

9. Electric igniters, primers, or detonators, electrically fired rocket and guided missile motors, electric or electronic ordnance fuzes, including VT fuzes, shall not be stowed in the same compartment with, or be exposed within five feet of, any exposed electronic transmitting apparatus or antenna or antenna lead, except where such electronic apparatus or antenna is a part of authorized test equipment of a weapon or is integral with a weapon containing such components, in which event special instructions pertinent thereto shall apply.

V. Torpedoes, Torpedo Air Flasks, and Accessories

1. Torpedo air flasks shall never be charged to more than 100 pounds above the prescribed working pressure. When the prescribed working pressure is for any reason altered, the new pressure designated shall be stamped on the flask near the charging valve.

2. The artificial cooling of torpedo air flasks during or after charging by spraying with water or by flooding the torpedoes in the tubes is prohibited.

3. Any cutting of torpedo air flasks, accumulators, piping, or other receptacles for compressed air is prohibited.

4. Torpedo air flasks in a fully charged condition shall not be transported, hoisted from one deck to another, struck below, etc., except when it is not possible to perform the operation efficiently and expeditiously with the air flasks partially charged.

5. In recovering a torpedo in the water the propeller lock shall be put on at the first opportunity and kept on until the torpedo is safely landed.

6. Because the filling material used in torpedo torch pots ignites spontaneously or forms poisonous gas when combined with water, or subjected to moisture, extreme care must be taken to follow existing Bureau of Ordnance instructions concerning the handling of torch pots.

7. The use of electric torpedoes involves hazards of mechanical injuries, electrical shock or burn, acid burns, and hydrogen explosion or combustion. Bureau of Ordnance instructions prescribe effective measures to prevent accidents and shall be rigidly adhered to at all times.

VI. Miscellaneous Ordnance Safety Precautions

1. Current instructions prescribe effective measures for the safe employment, operation, and service of catapults and their guns. In addition, all safety precautions pertaining to guns and ammunition, unless manifestly inapplicable, apply to catapult guns and their ammunition.

2. Smoke-making devices which misfire or have been in the water shall not be taken on board ship or inside buildings or structures on shore. Gas masks shall be worn when entering concentrated smoke clouds.

3. All personnel working with chemical ammunition shall be trained in the fundamentals of handling toxic chemicals and shall be familiar with the instructions pertaining thereto. They shall be equipped with adequate and effective equipment, including protective clothing and gas masks.

4. Pyrotechnic material shall always be kept by itself in regular pyrotechnic storage spaces, if such are provided, or in pyrotechnic lockers on upper decks. In using it, only a minimum amount shall be exposed.

5. All personnel shall keep clear of the possible exhaust path of rockets at all times.

6. Launcher-firing circuits shall not be tested when rockets are in the launchers.

7. In case of rocket misfire, personnel shall not approach the rocket for at least 10 minutes, nor until firing circuits are known to be open. This, at the discretion of the commanding officer, is not obligatory in time of action.

8. When a misfire occurs in handling demolition material, an ample margin of time shall be allowed before investigating the reason of misfire. A period of 30 minutes after the longest predictable delay has elapsed is considered ample.

9. In firing small arms, machine guns, and submachine guns, whenever a blow-back occurs, the bore shall be examined for foul bore before firing another round.