American Projectiles and Explosives - Explosive Bombs - Modified Series, and "M" Series (Part 1)

American Projectiles and Explosives



Explosive Bombs

Introduction

Classification


Army "Modified Mark" Series: Streamlined and filled with 100% TNT.  These are now obsolete.


Army "M" Series: Parallel sides, ogival nose, and boat tail; box type tail assembly construction; and filled with 50/50 Amatol sealed at both ends with TNT surrounds.  Some are now classified as obsolescent.


Navy "Mk" Series: Similar to design of Army bombs and filled with 100% TNT; discontinued, with some exceptions, under the standardization program.


Army-Navy "AN" Series: Similar to the "M" Series, except: (1) third suspension lug added at center of gravity and 180 degrees removed from other two lugs, and (2) base plate changed to the male type.

Since the development of the "AN" series, there have been two further modifications of the general-purpose (G.P.) bombs within that series, successively the "AN-GP" and "AN-GPA1" modifications.  The changes characteristic of these two modifications are dealt with in a later post.


Practice bombs: These dummy and special signs are of great variety and have probably received more attention with the advent of peace.

Army "Modified Mark" Series

General


This particular series of bombs was not satisfactory for war use and has been abandoned, except for a few of these bombs which are used for target practice and training purposes.  They are all of the same type and are intended for the same target use, general bombardment.  The accompanying chart contains the essential data concerning the bombs of this series.

Army "M" Series

Introduction

Prior to the organization of the AN Standardization Board in 1941, these bombs were designated as "Demolition H.E." bombs; under the standardization policy they were retitled as "General Purpose High Explosive (GPHE)" bombs.


Target: Ammunition dumps, railway engines and cars, all types of construction, and aircraft on the ground.


Body Construction: These bombs may be made by any one of the following methods: (1) From seamless steel tubing in which the nose of the bomb is formed by swaging and the tail by drawing to the necessary diameter; or (2) the case may be forged in one piece; or (3) it may be formed from cast sections welded together.  These bombs have female base filling plates.


Type of suspension: Horizontally, by dual lugs.


Construction of suspension lugs: Two eyebolts welded to the body along the longitudinal axis of the bomb.  The eyebolts are formed from bar steel, shaped in the form of a U, and then welded to the body.


Color and markings: Prior to 11 March, 1942, these bombs would have been painted yellow all over, with black manufacturer's markings; since that date they have been painted olive drab with a one-inch yellow band around the nose and base and a 1/4-inch band around the center of gravity.


Material of tail: Sheet steel


Tail construction: This type of tail consists of the following parts: (1) a cast-steel sleeve secured to the body of the bomb by a fin-locking nut; (2) four fins or vanes; and (3) internal box-type struts.  One vane and one strut are pressed from one piece of metal, and the four pieces are welded to one another and to the sleeve.


Type of filling: (1) 50/50 Amatol.  Since Amatol is hygroscopic, TNT surrounds are placed around the nose and tail booster sleeve to seal the Amatol from moisture; (2) 100% TNT, which will be stencilled on the bomb.  All of this series except the 100-pound M30 contain two built in Auxiliary Boosters M104, one in the nose and one in the tail, which contain tetryl.  The 100-pound M30 has the auxiliary booster in the nose only.  The Adapter Booster M102 (tetryl) is threaded to the base plate of all bombs in the series and receives the tail fuze.

Other bombs that carry an "M" designation, although not actually classified in the "M" series, are included in this section because they are obsolescent:

Characteristics of "M" Designated A.P. Bombs

Target: Armored naval craft, reinforced concrete, heavy steel construction.

Body construction: These bombs are converted seacoast artillery shells from which the rotating bands may have been removed.  The cases are single-piece steel forgings.  The modifications of the M52 and M62 differ only slightly in external dimensions and are all equipped with a nose cap for streamlining.

Construction of tail: A truncated tail cone is secured to the bomb base by a locking nut at the top of the fuze body; four fins or vanes are supported by internal box-type struts.

Next Time: Explosive Bombs - "M" Series (Part 2)

American Projectiles and Explosives - Anti-Personnel and Trip Mines

American Projectiles and Explosives



Anti-Personnel Mines

M2, M2A1, M2A2, M2A3, M2A3B1, M2A3B2, M2A4, and M2A4B2

M2A1

Overall Height: 6.5 inches
Case diameter: 2.5 inches
Base diameter: 5.25 inches
Weight of shell: 3 pounds
Weight of explosive: 0.4 pounds
Material: Steel
Lethal range: 60 feet

General: The M2 is a "bounding" anti-personnel mine, usually activated by a combination firing device.  The M2 has undergone several structural modifications to make it watertight.  The mine consists of an explosive shell contained in an upright thin-walled steel tube which is riveted to the base plate.  A cavity in the base plate contains the propelling charge, which consists of 20 grains of black powder in a small bag.  The tube containing the shell is sealed at the top by a metal cap.  A 1/4-inch pipe nipple threaded to the base plate serves as a connection for the firing mechanism.  Attached to the pipe nipple is a coupling into which is fitted the primer and igniter assembly.  The primer is protected during shipment by a hexagonal cap.


Modifications: The Mine M2 has been modified inthat the thin-walled steel tube is silver-soldered to the base (M2A1), or stamped (M2A3), instead of being riveted (M2).  The Mine M2A3B1 is a modification in which the tube, base, and nipple are cast in one piece.  The mine was approved but not issued, being too heavy.  The Mine M2A3B2 is a combination of the M2A3 and the M2A3B1, in that the base is cast but the tube and nipple are stamped to the base.  In the M2A4, which has two propellant bags, the tube and nipple are welded to the base, while, in the M2A4B2, the tube and nipple are welded to a base which is cast.  The M2A2 was a field modification thought to involve the use of a canvas bag.


Operation: The mine is similar to a small mortar.  When the fuze is actuated, the primer sets off the igniter.  The flash from the igniter sets off the propelling charge in the base plate.  The propelling charge projects the shell into the air and at the same time ignites the delay fuse in the base of the shell.  When the shell is at a height of approximately six feet above the base plate, the delay fuse fires a tetryl booster, which detonates the main charge.  The effective lethal range of the shell is 60 feet.


Color: The mine and firing device are dull olive drab in color except for the base flange, which is yellow.


Remarks: Each mine is packed in a corrugated paper carton with firing device, attached igniter, and four spools of wire.  Markings of "Olive Drab" or "Sand Color" on outside of container refer to the color of the wire.

M3

Body length: 5.4 inches
Body height: 3.5 inches
Body width: 3.5 inches
Weight: 9.6 pounds
Flaked TNT explosive: 0.9 pounds
Material: Cast iron
Lethal range: 30 feet
Color: Olive drab

Components: The mine consists of a rectangular cast-iron body containing high explosive, with fuze wells on two opposite sides and one end.  The filling hole on the other end is closed by a disc.  The mine is activated by the Fuze M7A1.


Remarks: On the surface, the lethal range for the mine is 30 feet.  If the mine is buried only deep enough to be camouflaged, the effective range is reduced to approximately 10 feet.

Exposure to moisture will not affect the operation of the mine; however, it is not water-proof and should not be planted where it will be immersed in water for more than a few days.






Practice Mine M8


The Practice Mine M8 is similar in appearance and operation to the M2A3.  Obsolete bodies of Mines M2 and M2A1B1 are utilized.  This mine does not contain a propelling charge in the base, as does the standard H.E. mine.  The propelling charge for projecting the cardboard projectile into the air is contained in the igniter charge on the base of the fuze.  The projectile contains a 12-gauge shotgun charge loaded with black powder to simulate the action of a live mine.  The primer and igniter, which has a delay of approximately five seconds, is activated by the M10 Combination Mine Fuze.  This fuze is a three-pronged firing device similar to the Combination Mine Fuze M6.

Trip Flares for Mine Fields

M48

General: Trip flares are used as a warning device in forwards edges of mine fields.  They can replace or supplement anti-personnel mines, especially when the field is being hastily prepared.  The flares give warning of approaching patrols entering the mine field and illuminate the area so that effective fire can be directed at intruders.

M48: This is a mortar-type parachute flare similar in appearance to the M2 series of anti-personnel mine.  The flare, weighing a total of five pounds, has a metal case which is painted olive drab.  In operation, the functioning of the igniter sets off the propelling charge, which projects the canister into the air and ignites the delay fuse in its base.  When the canister is 300 to 500 feet in the air, the delay fuse sets off the propelling charge in its base, which forces the flare and parachute out of the canister and sets off the ignition charge at the base of the flare.

The parachute unfolds, and the ignition charge ignites the flare, which burns for 20 seconds.  It illuminates effectively a circle of 300 yards radius.



M49


M49: This is a candle flare for use above the ground.  The flare, weighing a total of 1.4 pounds, has a laminated paper body with metal fittings which are painted olive drab.  Functioning of the flare is similar to that of the Fragmentation Hand Grenade Mk II.  The flare is installed with a taut trip wire which holds the trigger in an armed (vertical) position against the pressure of the trigger spring.  An additional pull of two to nine pounds on the trip wire pivots the trigger against the pressure of the spring, or release of the tension in the trip wire allows the spring to pivot the trigger in the opposite direction, either of which will release the cocked lever.  The pressure of the striker throws the lever off, and the released striker fires the percussion cap.  The flame from the cap ignites the black powder, which blows out the top and ignites the illuminant composition.  The flare produces a brilliant white light for approximately one minute.

The M49 can also be installed with a loose trip wire by having the trigger horizontal and attaching a trip wire to the safety pin.  A subsequent pull on the wire would withdraw the safety pin and permit the flare to fire.





Firecracker


Mk 2 Mod 0

General: The firecracker is used as a practice charge for booby traps and firing devices.  It produces a loud report accompanied by a bright flash and a considerable quantity of smoke, yet it is designed to reduce the hazard from flying particles such as are attendant upon the use of a standard potassium perchorate firecracker or flash salute.  The Firecracker Mk 2 Mod 0 contains no high explosive.  It is coated with a waterproofing material, yet it should be stored in a dry place.


Installation: The nipple of the coupling base of any standard firing device is pushed through the wax-filled hold int he hollowed end of the firecracker and rotated clockwise until at least two threads of the coupling base are inside the hollowed end.

Next Time: Explosive Bombs - Modified Series, and "M" Series (Part 1)

American Projectiles and Explosives - Anti-Tank Mines (Part 2)

American Projectiles and Explosives

Anti-Tank Mines




M6

Diameter: 12.5 inches

Height: 3.25 inches
Total weight: 20 pounds
TNT filler weight: 12 pounds
Material: Steel
Color: Olive drab

Components: The mine consists of a loaded mine body, fuze, and pressure-plate plug.  The steel body is cylindrical, with a carrying handle attached to the bottom.  Assembled to the mine body is a round pressure plate, 7 and 1/2 inches in diameter, containing the reversible pressure-plate plug which covers the fuze well.  The pressure plate is supported internally by circular Belleville springs and sealed against moisture by a rubber diaphragm.  In addition to the primary fuze well, supplementary fuze wells are located on the side and on the bottom of the mine for use in anti-lifting or booby-trap purposes.


Remarks: For booby traps or anti-removal devices, after the main fuze is installed, any standard firing device may be attached to the supplementary fuze wells by using the Activator M1.  This activator is a plastic adapter approximately 2 inches long, which contains a tetryl booster charge.

This fuze myst not be used with the Anti-Tank Mine M7.

M7A1

Length: 7 inches
Width: 4.5 inches
Height: 2.5 inches
Total weight: 4.5 pounds
Tetryl filler weight: 3.25 pounds
Material: Steel
Color: Olive drab

Components: This mine can be used as either an anti-tank or an anti-personnel mine.  The body is a rectangular steel container filled with high explosive.  The fuze well is located in the center of the top surface, and at one end is an activator well that will accommodate any standard firing device with a Corps of Engineers' blasting cap.  The pressure plate is shaped to the contour of the mine body and is slotted so that it may be guided by rivets in the sides of the mine body, into position over the fuze.  A small circular pad on the underside of the pressure plate bears against the head of the fuze.


Remarks: For a booby trap or anti-personnel mine, any standard firing device may be attached to the side fuze well.





Improvised Mines

Bangalore Torpedo

No picture available

Special torpedo caps are furnished with each box of ten bangalores, to adapt the bangalore torpedo for use on an anti-tank mine.  Pull-firing detonators are furnished separately.  To assemble the bangalores for use as an anti-tank mine, insert detonators in two torpedo caps; place a safety pin through the torpedo-cap ears and the detonator loop of each; and snap a torpedo cap onto each end of the torpedo, so that the detonator fits into the cap well.  Lay the torpedo on the ground across a wooden block and drive eight-inch spikes on drift pins into the ground as close to the ends as possible.  Pass the detonator wire through each detonator loop, and attach the wire to the spike.  Make sure there is no tension on the detonator wire.  Withdraw the safety pin.  The mine is now armed and ready for use.



2.36-inch A/T Rocket

No picture available

The A/T Rocket M6 may be employed by placing the rocket, nose-up in its container, in a hole about two feet deep, either ina  roadbed or horizontally on the side of a cut or bank.  It can be set to fire electrically by arranging a circuit containing the rocket, a battery, and an improvised circuit closer.  Connections to the rocket are made on the ignition wires: one from the brass ring on the nose, the other from the fins.  Ordinary field telephone wire will serve; the battery and connections should be protected from water if necessary.

The container cap is removed and the other end knocked out.  The container is thus a guide for the rocket.  A hole is punched in the container cap, through which the electric firing-device wire (or trip-wire) are run.  When connections have been made, the container cap is slid in place over the fins to protect the contacts from fouling.  The rocket safety pin is removed; the container tube is slid over the rocket and joined to the cap; and the assembly is placed in the hole.  Loose dirt and leaves are then placed over all of the rocket except the nose; the nose is concealed by covering with leaves or light bunches of grass.  Care must be taken not to bump the nose, as the rocket is completely armed when the safety pin is removed.







Practice Mines


  General: Practice mines are used in training.  These mines can be identified by their blue color and white markings.


M1: The Practice Mine M1 consists of three components: an empty mine body, a spider, and a fuze.  The parts are similar in construction to the high-explosive mine, except that the body has five one-inch holes equally spaced around the side.  The explosive filling consists of a caliber .32 blank cartridge in the fuze, 100 grains of red phosphorus, and 60 grains of black powder.


M1B1: The Practice Mine M1B1 is made of sheet metal and resembles the service mine, except that the filling hole is in the bottom of the mine body.  The body is sand-filled to weight before it is issued for use in practice.  Four sections are cut out of the top of the body near the fuze well, to permit the passage of smoke.


T8E1: The Practice Mine T8E1 simulates the standard Mine M6.  It uses the Practice Fuze T20, which simulates the M600, but gives a puff of smoke instead of detonating the mine.  Four sections cut out of the top of the body near the fuze well permit the passage of smoke.


M10: The Practice Mine M10 simulates the standard Mine M7A1.  It is loaded with 3.4 pounds of inert filler, consisting of Santo wax M, 50%, plaster of paris, 12%, and powdered red iron oxide, 38%.  It uses the Practice Fuze T20.  Four sections cut out of the top fo the body permit the passage of smoke. 

Next Time: Anti-Personnel and Trip Mines

American Projectiles and Explosives - Tree Suspension Device and Anti-Tank Mines (Part 1)

American Projectiles and Explosives

Tree Suspension Device

M18

General: The Tree Suspension Device M18 for smoke grenades is designed to provide a quick and simplified means for suspending standard burning-type smoke hand grenades from trees and foliage to permit emission of smoke above forests and foliage, where it is more readily visible to air observer.  It must be used with the Chemical Grenade Projection Adapter M2 assembled to any of the following hand grenades: AN-M8, M16, or M18.


Description: The device has a small cardboard tube into which is loosely packed about a ten-foot length of heavy rayon line.  Attached to each end of this line are two light metal cables, one for fastening to the body of the grenade and the other for fastening to the stabilizer of the Adapter M2.  It also has a heavier metal set-back ring to replace the set-back band issued with the chemical grenade projection adapter.  This heavier set-back ring retains the grenade safety lever in a safe position after removal of the fuze safety pin, releases the safety lever by set-back action upon being fired, and separates the grenade from the adapter by set-back action against the clips of the adapter, upon being fired.


Assembly: The device is assembled for use by slipping the double loop of cable over the grenade body under the safety lever.  The set-back ring is slipped over the bottom of the grenade so that it holds the safety lever in place, and the set-back band issued with the grenade is discarded.  The grenade is assembled to the adapter, and the single loop of cable is slipped over the adapter fins and secured to the stabilizer tube.  The rifle or carbine is prepared for firing in the usual manner, using positions 3 or 4, at an angle of elevation of 50 or 70 degrees and, normally with the butt of the gun supported by soft earts or other resilient material to avoid the possibility of cracking the stock.


Operation: Upon firing, the entire assembly is projected forward, and the set-back ring strikes the clips sharply, separating the grenade from the adapter.  Because of the construction of the adapter, it tends to slow down as soon as it is separated from the grenade.  In doing so, pulls the rayon line from the cardboard tube.  The grenade then flies through the air, with the adapter trailing at the end of the cord.  Upon reaching a tree, the cord and adapter become entangled on branches or foliage, suspending the smoking grenade.

Land Mines




Introduction

Mine Types: There are two common types of land mines: anti-tank and anti-personnel.  Anti-tank mines, designed to immobilize track or wheeled vehicles, vary in the amount of explosive they contain, the normal charge being 6 to 12 pounds.  They are used in mine fields or road blocks.  Anti-personnel mines are used primarily to produce casualties to personnel, and, secondarily, to give local security and warning.  The explosive charge varies from 1/4 to 4 pounds.  Other, less common, mines are classified in the general categories of improvised, dummy, and practice.


Firing Devices: Firing devices are classified in accordance with the method of their initiation; that is, pressure, pull, tension-release, or pressure-release.  The initiating action causes the device to function by chemical reaction, friction, percussion, or the closing of an electrical circuit.

Anti-tank mines generally have a main fuze which is employed as the primary initiating device; however, some anti-tank mines have supplementary activator wells on the side and bottom for booby trapping.


Marking: Mines can be identified by their color and markings.  Land mines are generally painted lusterless olive drab with a yellow base and black markings, while practice mines are painted blue with white markings and dummy mines are black.


Army and Navy Types: The Navy does not design land mines, but it has produced three firing devices for use with demolition charges - the Firing Devices Mk 1, Mk 3, and Mk 15.  The Navy also produced the practice firecracker.

Anti-Tank Mines




M1A1 (Obsolete)

Diameter: 8 inches
Height (with spider): 4 inches
Height of body: 2.75 inches
Total weight: 10.6 pounds
Cast TNT weight: 6 pounds
Material: Steel
Fuzing: M1A1, M1A2

Components: The metallic Anti-Tank Mine M1A1 has three main components: loaded body, fuze, and spider.  The spider fits over the fuze to increase the effective size of its head.  The steel body is a squat cylindrical container of light steel filled with high explosive.  A carrying ring is attached to its side.  The flanged rim around the top is notched for attaching the spider.  In the center of the top is the cavity for the fuze and booster; the booster fits into the cavity and locks into place.  The spider is a ring with two cross members pressed from a single sheet of metal.  Hooks on the spider engage the flange on the mine body, and the center hub of the spider rests on the striker head of the fuze.  When the mine is packed, the spider is placed over the bottom of the steel body to save space.


Arming: The safety fork is not removed until after the mine is laid; and, after removal, the fork is left beside the mine, attached to its cord, never between the body and the spider.  Before the mine is taken up, the safety fork is replaced.


Color: The bottom and 3/4-inch of the side are painted yellow; the rest of the mine is painted olive drab.


Remarks: The M1, the original model, is no longer being manufactured or issued.  The principal difference is that, in the Mine M1, the booster is an integral part of the fuze; in the Mine M1A1 the booster is a separate part and issued assembled in the fuze cup of the mine.

Protective bag covers made of moisture-resistant, mildew-proof fabric are provided with this mine to prevent foreign matter from working between the mine body and the spider.  The cover is cylindrical in shape, 8.75 inches in diameter, 9 inches high, and open at one end.  The Mine M1A1 is being replaced by the M6.

M4 (Obsolete)

Diameter: 8 inches
Height (with spider): 4 inches
Total weight: 10.6 pounds
Cast TNT weight: 6 pounds
Material: Steel

Components: The metallic Anti-Tank Mine M4 is identical to the M1A1 type except for the booster, the fuze, and the activator wells.  The M4 has one activator well on the bottom and one on the side.  Since the booster, after loading, becomes an integral part of the mine, and since the M1A1 and M4 boosters and fuzes are not interchangeable, it is especially important that the Mines M1A1 and M4 and their respective fuzes be kept separate.  However, the two mines are assembled, armed, and employed in the same manner.  The advantage of the Mine M4 is that the internal construction of the M4 fuze makes it safe to re-use, because it is not made more sensitive by repeated light blows.


Booster: The M4 booster is identical with M1A1 booster, except that it has a flat top with a crossed scar to insure rupture of the booster shell by the detonator, while the M1A1 booster has a cavity int he top to receive the protruding primer and detonator of the M1A1 fuze.


Arming: The safety fork is removed from the fuze by pressure of the thumbs on the prongs.


Color: The bottom and 3/4-inch on the side are painted yellow; the rest of the mine is painted olive drab.


Remarks: The Mine M4 is being replaced by the M6.

The M4 also has a protective cover bag.

M5

Diameter: 10 inches
Height: 5.5 inches
Total weight: 14.5 pounds
Weight of filler: 5.6 pounds
Type of filler: TNT or Tetrytol
Material: Pottery and impregnated felt

Components: The cylindrical mine body consists of a ceramic bowl containing the high explosive, with a ceramic plate which acts as the spider.  These components are separated by a cushion of rubber or similar material and enclosed in asphalt-impregnated felt and tarred paper.  There is a threaded opening in the top of the mine for assembly of the fuze and a bakelite plug in the bottom, which may be removed for the attachment of an anti-removal device.


Color: The mine is painted olive drab and marked in yellow


Remarks: This is a non-metallic mine in order that it may not be detected by an electro-magnetic mine detector.

An anti-lifting device may be attached by removing the rubber plug in the bottom of the mine; however, use of a metal device tends to defeat the purpose of designing the mine and fuze with no metal parts.

This mine is considered a substitute standard item by the Army Ordnance Department.

Next Time: Anti-Tank Mines (Part 2)