Monday, 27 March 2017

British Explosive Ordnance - Hand, Rifle, and Anti-Tank Grenades







British Explosive Ordnance





Hand and Rifle Grenades Introduction


General

The various types of grenades used by the British are the anti-personnel, anti-tank, smoke, illuminating, and incendiary grenades.  The individual grenades are generally hand thrown, rifle projected, or, in some cases, may be either hand thrown or rifle projected.

The British armed forces use anti-personnel grenades of both the offensive and the defensive types.  Anti-tank grenades vary widely in principle and construction, and sometimes incorporate a cavity charge to achieve greater penetration.  Smoke grenades are of simple construction, and employ a white phosphorus charge, a burning smoke composition, or a combination of the two to produce a heavy smoke screen.  The rifle illuminating grenades consists of a basically similar series of grenades, which vary mainly as regards to filling.  The single incendiary bomb in this section is not designated as a grenade, but is included because of its similarity and use.

Grenades are commonly initiated by firing mechanisms resembling the Bouchon type igniter, by all-ways action fuzes, or by integral striker assemblies.  Special items are equipped for special initiation, such as the Grenade No.76, which is ignited by reaction of its contents, when exposed to air, or the Grenade No.75, which employs two separate chemical igniters to initiate its explosive train.


Designation

Grenades generally follow the usual British system of designation.  They are identified by a "Number", corresponding to the US Navy "Mark", and a Roman numeral "Mark", corresponding to the US Navy "Modification."  Recent issues have the mark written in Arabic numerals.


Color and Markings

Grenade bodies are usually painted a solid color to indicate their use, as follows:

Anti-Personnel ------ Black
Anti-Tank ------ Buff
Smoke ------ Green
Illuminating ------ Buff
Incendiary ------- Red

There are some departures from this listing, but it can be followed as a general rule.

A red band, generally located near the top of an H.e. grenade, indicates that the grenade is filled.  A ring of red crosses signifies that the filling is suitable for tropical storage.  The type of filling is identified by a colored band or bands around the center of the grenade body.  The abbreviation of the filling is stencilled on this band.

Each grenade has the grenade designation stamped, cast, or stencilled on the body.  In addition, the manufacturer's initial or symbol, and the month or year of manufacture are also shown.  When the grenade is filled, the initials or symbol of the filling depot,t he type of filling, date of filling, and filling lot number are stencilled on the grenade body.

In some cases, special markings may supplement or replace the standard markings.


 Firing Mechanisms

One type firing mechanisms commonly used to initiate British grenades, is similar in principle and operation to the Bouchon type igniter used in US grenades.  These striker mechanisms employ a fly-off safety lever which is retained until use by a safety pin, a pivoted, spring-loaded striker retained by the safety lever, a percussion cap, a safety fuse delay, and a detonator.  The detonator is a separate unit, which is inserted into the grenade beneath the striker mechanism shortly before using.  The several striker mechanisms which are in use differ from one another mainly in the shape of the body or safety lever, material of construction, or color of the safety lever.

The striker mechanisms used in smoke grenades filled with a smoke composition do not have a detonator.  The composition is ignited by a piece of primed cambric and priming composition, which are initiated by the delay fuse.  W.P. filled grenades employ detonators to burst the container and expose the filling to the action of the air.

Many grenades employ specialized igniters and fuzes, which are peculiar to them.


Fuze No.247

The Fuze No.247 is an "all-ways" action fuze commonly used in a number of British grenades.  The Fuze No.247 Mk I has a body which is closed at one end by a closing cap and has a flash channel at the opposite end.  A striker creep spring, cap pellet, and a lead ball are located inside the fuze body.  The striker has a concave head, into which the ball fits, and a split striker point.

The creep spring separates the striker and cap pellet.  A safety pin is inserted through the fuze body and the striker body, and has a length of fabric tape with a lead weight on the end fastened to its head.  A plastic cap fits over the fuze body to hold the tape and weight in place.

The Fuze No.247 Mk II differs from the Mk I in that it has a single point on the striker, and uses a more powerful detonator, instead of a percussion cap, in the cap pellet.  The No.III is the same as the No.II, except that the closing caps is cast in one piece with the body, and is closed instead by a plug in its base.  Different lengths of tape are used to change the arming times of the fuze.

The Fuzes Mk I and Mk II are obsolete and will not be used for future issues.

The Fuze No.247 is very sensitive when armed, and should be handled accordingly if encountered in this condition.





A/P Rifle or Hand Grenade No.36M Mk I (Obsolete)


Overall length: 4 inches
Diameter: 2.4 inches
Total weight: 1 pound, 11.25 ounces (approx.)
Delay: 4 seconds for hand grenades; 7 seconds for rifle grenades

Color: Black
Markings: Green band around center; red band or crosses around top

  
Description: This grenade consists of a lemon-shaped, cast-iron body filled with high explosive.

The body has three holes in it; one in the base for priming, one near the top for filling, and one on the top through which the striker protrudes.  The body is serrated and relatively thick, so as to give good fragmentation.  A center piece, containing a striker and spring, a primer delay train, and a detonator, is located within the body and surrounded by cast explosive.

The striker is held up and the striker spring is held cocked by a lever which fits into a slot in the top of the striker.  The lever is secured by a safety pin passing over it and through holes in two shoulders, which project on the outside of the body.  The lever is shaped with two small projections, which fit into notches in these shoulders to provide a pivot.  The lever projects down the side of the grenade body, matching the body contour.  The filling hole is closed by a screw plug.  The base plug threads into the base opening and is itself threaded to receive a 2.5-inch diameter metal gas check disc for use when the grenade is fired from the rifle projector.

The igniter consists of a primer cap, a short length of safety fuze, and a detonator.  The Igniters Mk V and Mk VI, which differs only in the composition of the safety fuze, incorporate a 4-second delay for use with hand grenades.  These igniters can be identified by the white safety fuze employed.  The Igniters Mk II and Mk III incorporate a 7-second delay for us with rifle grenades.  They can be identified by the yellow safety fuze used, and the fact that the detonator body of the Mk II is copper, while that of the Mk III is aluminum.


Operation: Priming consists of removing the base plug, inserting the igniter set, and replacing the base plug.

When the grenade is to be thrown, it is held with the throwing hand over the safety lever, and the safety pin is then removed.  When the grenade is thrown, the lever is released.  The striker spring forces the striker downward, rotating the lever about its pivot and throwing it off.  The striker hits the cap igniting the delay, which, in turn, sets off the detonator and the main filling of the grenade.

If the grenade is to be fired from a rifle discharger, it must be primed with the 7-second delay igniter and the gas check disc must be threaded tightly into the base plug.  The grenade is placed in the discharger, base first.  When the grenade is inside the discharger and the striker lever is held by the sides of the discharger, the safety pin is removed.  As the grenade is fired and leaves the discharger, the safety lever is no longer retained and flies off, allowing the striker to hit the cap.


Remarks: This grenade is packed and marked as a hand grenade with a 4-second delay igniter, or as a rifle grenade with a 7-second delay igniter.

No weight of explosive is specified, as the grenade is filled to capacity.






A/P Hand Grenade No.69 Mk I (Obsolete)
   

Overall length: 5.5 inches
Diameter: 2.375 inches
Total weight: 13 ounces
Filling: Amatol 80/20, Lyddite, or Baratol 20/80
Filling weight: 3.25 ounces
Fuze: No.247 Mk I, II, or III
Delay: None

Color: Black
Markings: The grenade has a band of red X's on the upper body, and a colored filling band around the base section.


Description: This grenade is a light, impact-firing grenade for offensive action.  The body is made of bakelite.  The area of burst is very limited, and it can, therefore, be thrown while standing in the open.  The two-piece body threads together in the middle.  There are a filling hole and plug and a priming hole and plug in the base section.  The bakelite holder for the fuze threads into a large indentation in the top section.  There is a detonator well running lengthwise through the filling.

The fuze is all-ways acting.  The striker rests on a creep spring inside a striker sleeve.  The base of the sleeve carries a primer cap.  The striker head is cut to receive a lead ball.  The closing cap is shaped so that a convex surface fits over the ball.  A safety pin passes through a hole in the fuze holder and beneath the striker head to rest on the top of the striker sleeve.  A length of tape is attached to this pin.  The tape winds around the striker holder and has a small lead weight on its free end.  A light bakelite cap threads over this whole assembly and is held securely in place by a piece of adhesive tape.


Operation: The detonator is inserted open and first into the base hole, and the base plug is replaced.  The adhesive tape is then removed and the safety cap unscrewed in one half of a turn/  After the cap is removed, the tape must be held in place by the forefinger and thumb.  When thrown, the weight on the end of the tape causes the tape to unwind and pull out the safety pin.  Only the creep spring is now holding the striker away from the primer cap.  On impact, the striker is forced into the primer cap, which initiates the detonator and explodes the grenade.


Remarks: Once the tape has unwound and the safety pin is free of the striker, the grenade is in a very sensitive condition and should be carefully disposed of.








A/P Hand Grenades No.70 Mk I (Obsolete), Mk II (Obsolete), and Mk III (Service),                and No.71 (Obsolete)
   

Overall length: 4.5 inches
Diameter: 1.75 inches
Total weight: 1 pound

Filling:
-Mk II: Baratol or Amatol
-Mk III: RDX/TNT

Fuze: No.247 Mk I, II, or III
Delay: None

Markings: Body is banded near the top in red and semibanded near the middle with two yellow bands separated by a green band.


Description: The Grenade Mk II consists of a cast-iron body, a fuze adapter, a base plug with a rubber spigot, and a filling-plug hole.  The body is cup-shaped and threaded internally at the top to accommodate a fuze adapter.  It is closed at the bottom by a threaded base plug to which is cemented a spigot.  A rubber washer is interposed between the plug and the body.  The adapter of zinc-base alloy is threaded internally to house a D.A. Percussion Fuze No.247, Mk III, and is formed with a central perforation to position an aluminum detonator tube.  A rubber washer is positioned between the fuze and the body.  The filling hole in the side of the body is closed by means of a molding plug and a rubber washer.  The body contains a filling of Baratol or Amatol.

The Grenade Mk III differs from the Mk II in that the filling hole and the thickneing of the case at that point have been completely eliminated, and the Amatol or Baratol filling has been replaced by RDX/TNT 50/50, with a C.E. pellet.


Operation: The adhesive tape securing the fuze safety cap and the cap itself are removed.  When the grenade is thrown, a weighted strip of tape withdraws the safety pin to arm the fuze.  On impact, the striker overcomes the creep spring, and fires the cap, which initiates the detonator and, in turn, the main filling.


Remarks: The Grenade No.70 Mk I was allocated to a small number of experimental designs not issued for service use.

The Hand Grenade No.71 was a larger grenade of the same type construction as the No.70, weighing approximately two pounds.  The Grenade No.71 was never adopted for service use.











A/P Hand Grenade No.82 Mk I (Service)


Total weight: 2 pounds (approx.)
 Filling: Plastic Explosive
Filling weight: 1 pound (approx.)
Fuze: No.247 Mk I, II, or III, with short 4.5-inch tape
Delay: None

Color: Fuze, black; cup, buff; bag, black
Markings: Standard


Description: The body of this H.E. grenade, formerly known as the "Gammon Bomb", consists of a fabric bag, open at each end.  The lower end of the bag is gathered, and an elastic band inserted around the edge, while the upper end fits under a steel cup.  The edge is clamped between the cup and the flange of a tinned plate fuze housing by four equally spaced rivets.  A tin-plate cap, to the lower end of which is secured an aluminum primer tube, is screwed over the fuze housing.

The grenade is fuzed with the Fuze No.247 wound with 4 and 1/2 inches of tape instead of the usual 12 inches.  The primer tube contains a C.E. pellet over which is placed a felt washer.  A central perforation in the pellet accommodates a Detonator No.78 Mk I with a felt disc inserted between it and the bottom of the primer tube.

The grenade is issued with the bag empty.  The charge of plastic explosive is inserted through the bottom of the bag under local arrangements.


Operation: First the grenade is primed and the plastic explosive inserted.  The adhesive tape is then removed and the safety cap unscrewed in one-half of a turn.  After the cap is removed, the tape must be held in place by the forefinger and thumb.  When thrown, the weight on the end of the tape causes the tape to unwind and pull out the safety pin.  Only the creep spring is now holding the striker away from the primer cap.  On impact,t he striker is forced into the primer cap, igniting the delay, which initiates the detonator and explodes the grenade.


Remarks: The No.82 Mk I/I differs from the No.82A Mk I in that it has a rot-proof fabric bag.

This grenade has a general anti-personnel application, but is used mainly by airborne force as an anti-tank weapon.










Anti-Tank Grenades




A/T Rifle Grenade No.68 Mks I-VI (Obsolete)
   

Overall length: 7 inches
Diameter: 2.5 inches
Total weight: 1 pound, 15.5 ounces
Filling: RDX/BWX 91/9, P.S., Lyddite, C.E/TNT 30/70 or Pentolite
Filling weight: 5.5 ounces
Delay: None

Color: Buff
Markings: Red filling band around top and green band around center of body.


Description: The grenade consists of a steel or Mazak bell-shaped body fitted with a tail.  The open end of the body is fitted with a  thin metal cavity liner, which forms a hollow in the H.E. fitting.  The cup is secured by a screw collar.  The dome of the body is bored to carry the detonator holder and threaded to receive the tail section.  The tail has four straight vanes and is centrally recessed to receive the striker.  A copper shear wire and safety pin secure the striker in position.  The pin is removed before the grenade is fired.  The gas check plates are secured either by metal rivts, or in an integral casting with the fins of the grenade.

The following differences exist among the carious marks of this grenade.  The Grenade Mk I has small tail vanes and an additional small set of vanes on the body.  A steel gas check is secured to the tail by a bakelite or brass screw.  The brass cavity liner is hemispherical in shape.

In the Grenade Mk II the small vanes were removed from the body and the tail vane enlarged.  The gas check was secured by a brass screw or by crimping the tail.  In the Mk III a cylindro-conoidal steel cavity liner was substituted for the hemispherical liner previously used.  The gas check was either secured by crimping, or was made of Mazak cast integrally with the tail unit.  The Grenade Mk IV employed a new type of detonator holder, and had the tail unit and gas check cast integrally of Mazak.  The Grenade Mk V also employed the new detonator holde,r but used the steel gas check secured by crimping.

The Mk VI was produced in the United States.  The tail unit consisted of a steel tail tube to which the tail fins were spot welded.  A wooden plug, secured by a shoe rivet, closed the after end of the tail tube.

Operation: Before the grenade is fired from the discharger, the safety pin must be removed.  The striker is located slightly away from the rear of the tube containing it.  On setback, the striker moves to the rear, shearing the shear wire.  It is then held only by the creep spring.  On impact, the striker overcomes the creep spring and hits the detonator to explode the grenade.  The effective range is given as 50 to 75 yards.







A/T Hand Grenade No.73 Mk I (Obsolete)
   

Overall length: 9.5 inches
Diameter: 3.25 inches
Total weight: 4 pounds
Filling: Polar ammon gelatine dynamite
Filling weight: 3.25 pounds
Fuzing: No.247 Mk I, II, or IIII
Delay: None

Color: Buff
Markings: Red filling ring around the upper body and standard markings.

  
Description: This is a thin-walled grenade intended for use against armored forces vehicles, but more generally used in demolition work.  The grenade consists of a tin-plate container with a top of the same material, which screws onto the body by means of interrupted threads.  A recess in the middle of the lid is threaded to take the Fuze No.247.  The fuze is cemented in position and issued with the grenade.  The detonator tube screws into the lower portion of the fuze housing.  A commercial Detonator No.8 is used.  A felt disc at the top of the filling absorbs any exudate from the explosive.  A strip of adhesive tape secures the lid to the body on issue.

Operation: Before use, remove the adhesive tape, take off the lid, and unscrew the detonator holder.  Insert the detonator, and replace the holder and lid.  Then remove the adhesive tape from the fuze and unscrew the fuze cap.  After the cap is removed, the safety tape must be held in place by the thumb and forefinger.  When thrown, the weight on the end of the tape causes the tape to unwind and pull out the safety pin.  Only the creep spring now separates the striker and primer cap.  On impact,t he striker is forced into the primer cap, which initiates the detonator and explodes the grenade.








A/T Hand Grenade No.74 Mks I and II (Obsolete)
   
   
Overall length: 9 inches
Diameter: 4.5 inches
Total weight: 2.25 pounds
Filling: Nobel's No.823 explosive
Filling weight: 1.25 pounds
Delay: None

Color: Body, buff; handle, black
Markings: Red filling band around the upper body.


Description: The Grenade No.74 Mk II consists of a globular bakelite flask containing the explosive filling, which is primarily nitro-glycerine and nitro-cellulose, a bakelite handle containing the firing mechanism, and an adhesive-treated sock.  During filling, an air space is left to allow for expansion of the explosive.  The sock covers the flask and is very sticky.  The handle threads directly into the flask.  Within the handle is a sharp striker and a striker spring.  A safety lever fits under a nut on the head of the striker and down the handle to hold the striker up and the spring compressed.  The top of the striker is spread to retain the nut.  A safety pin passes through holes in projections on the safety lever, through the handle, and under the striker.  The flask is closed at the neck by an externally threaded safety plug into which the detonator assembly is inserted immediately before use.  The detonator assembly consists of a percussion cap, a 5-second delay, a detonator, and a C.E. pellet.

A light metal container, made in two hemispherical sections joined by a spring hinge, clamps over the sticky flask for protection during handling and shipping.  Before the grenade is used, this cover must be removed by releasing the spring clip at the neck of the case.  Several small rubber projections on the inside of the case separate it from the adhesive sock.

The detonator assembly is placed into the well in the flask.  The handle is then screwed into the neck of the grenade and the casing removed.  The handle must be grasped firmly with the hand over the safety lever before the safety pin is withdrawn.  After the safety pin is removed, the handle is released and the striker spring forces the striker down, throwing off the safety lever and striking the percussion cap.

This grenade has been designed for use against armored-force vehicles.  It is supposed to stick to the target, but will not adhere to a sloping surface, should it be wet, muddy, or oily.  Although it can be thrown for short distances, far better effect will be obtained if the grenade is placed directly on the target with enough force to break the flask.

The viscous explosive filling tends to run at moderate temperatures; thus storage temperatures must be kept low.  The grenades are definitely subject to sympathetic detonation.


Remarks: The Grenade No.74 Mk I is similar to the Mk II in operation, but differs in several constructional details.  The Mk I had a glass flask which proved to be too fragile and was replaced by bakelite in the Mk II.  The Mk I was filled to capacity with explosive and consequently leaked if expansion took place.  The handle was fastened o the body by a plastic retaining ring which gave too weak a joint.  The blunt striker was a frequent cause of misfires.  The Mk I and II also employ slightly different detonator assemblies.







A/T Hand Grenade No.75 Mks I, II, and III (Service)
   


Overall length: 6.5 inches
Width: 3 and 5/8 inches
Height: 1 and 7/8 inches
Total weight: 2.25 pounds
Filling: Nobel's No.704B, Ammonal, Burrowite, or TNT (all with exploders or C.E. pellets)
 Filling weight: 1.75 pounds

Fuze:
-Mk I: Grenade Igniter No.75 Mk II
-Mk II and III: Detonator No.83

Delay: None
Pressure to fire: 300 pounds

Color: Buff
Markings: Cap painted pink when Burrowite or Ammonal filled; red filling ring below cap indicates Victor Powder or Exp. No.673 exploder; ring of red crosses indicates Polor Dynamite exploders.


Description: The Grenade Mk I consists of a 1-pint capacity, flat, tin-plate can, which is rectangular in shape, and has rounded corners.  It is filled through a hole in the end, over which a tin cap is screwed and cemented to provide watertightness.  On one side of the can are two metal pockets with slots cut in them, which form the detonator holders.  These pockets have malleable metal tabs which are bent to close them.  The striker plate is supported above the detonator holders by two brackets, one on each end of the can.  The striker plate is a light metal plate with a transverse projection on the bottom which serves as a striker.  It is secured to the brackets by two bent tabs, so that the striker is immediately over the slots in the detonator holders.  The principal differences between the Grenades Mk I and Mk II lie in the fuze pockets, which in the Mk II are set at an angle for easier insertion of the fuze assemblies, and in the detonator assemblies.  The Grenade Mk III is similar to the Mk II, but has no filling cap.  It is filled with 1.75 pounds of TNT, and two C.E. pellets.

The fuze for the Grenade No.75 Mk I consists of an Igniter No.75 Mk II and a detonator.  Two of these units are used with each grenade.  The igniter is a tin-plate tube closed at one end by flattening, and it is painted red.  It contains an acid-filled glass ampoule, and ignition composition.  A rubber tube is roleld into the igniter.  The detonator is an aluminum tube open at one end, and is smaller in diameter than the igniter.  The detonator is slipped into the open end of the igniter, and the rubber tube rolled over the joint to provide waterproofing.

In the Grenades Mk II and Mk III, the detonator units are manufactured and issued in one piece.  Each Detonator No.83 consists of a bakelite holder containing a glass ampoule, the end of which is sealed with wax.  A striker pin is held in the top of the holder by means of a red cellulose seal.  The detonator fits tightly over a tubular projection on the holder, and is sealed on with glue.  As with the Grenade Mk I, two assemblies are provided with each mine.  Pressure on the plate forces the striker pins into the ampoules, which fire the detonators and thus the main charge.  The Grenade Mk II uses the C.E. filled Detonator No.83 Mk I, while the Mk III grenade uses the RDK filled Detonator No.83 Mk II, which is also designated No.96 Mk I.

The grenade is so shaped that when thrown it will come to rest with the striker plate either on top of underneath.  It will operate equally well in either position.




Operation: For the Grenade No.75 Mk I, insert the open end of the detonator into the open end of the igniter.  Then roll the rubber tube on the igniter to cover the joint.  This provides a water-tight seal.  Insert a detonator assembly, detonator end first, into each of the pockets of the detonator holder through the hole in the striker-plate bracket.  Bend over the metal tabs, thus securing the detonator assemblies int he pockets.  The red painted portions of the assemblies should now be visible in the slots of the detonator holders.  The grenade is thrown or placed so that it will be run over.  The pressure of the vehicle upon the striker plate will force the strikers through the slots in the detonator holders, crush the igniter tubes, and break the glass capsules containing nitric and sulphuric acid.  The action of the acid on the potassium chlorate and charcoal ignition composition produces an immediate flash, which sets off the detonators and explodes the grenade.

In the Grenades No.75 Mk II and Mk III, the igniters are inserted in their pockets and the tabs bent into place to secure them.  When the grenade is run over,t he striker pin crushes the glass ampoule and grins the broken glass and contained igniter composition together, igniting the composition.  The resultant flash initiates the detonator, which explodes the grenade.


Remarks: When the Grenade No.75 is filled with Ammonal, the designation is changed to No.75A. Ammonal is about 80% as powerful as the regular fillings.

The Grenade No.75 is actually employed mainly as a land mine for defense against armored cars, tanks, and other vehicles.  It will disable light tanks and vehicles and is used principally for hasty minefields.

The Grenade No.75 is often referred to as the "Hawkins" grenade.









A/T Rifle Grenade No.85 Mks I, II, and III (Soon in Service)
   

Overall length: 10.5 inches
Diameter: 1 and 7/8 inches
Total weight: 1 pound, 6 ounces
Filling: RDX/TNT 50/50
Filling weight: 4.5 ounces
Fuzing: No.430 Mk I and No.431 Mk I
Delay: None


Description: The Grenade No.85 is an anti-tank, cavity-charge grenade patterned after the US Army M9A1 and similar in construction.  The Mk I is fitted with Fuze No.430 Mk I, which will function satisfactorily on impact up to 45 degrees from the normal.  There is no safety pin to withdraw, and the fuze does not arm until the grenade is fired.  The Grenade Mk II has the same head but is fitted with t he Fuze No.431 Mk I, which differs from the Fuze No.430 in that it has a longer booster, and is easier to assemble and inspect.

The Grenade No.85 Mk III is similar to the Mk I except for the fact that the lower body is wire wrapped to increase fragmentation, allowing a dual employment as either an anti-tank or anti-personnel grenade.  The tail tube and fuze are made of a light alloy in the Grenade Mk III.  This change of material gives the fuze the designation No.431 Mk I/L.


Operation: Upon firing, the diaphragm is reversed by gas pressure, forcing the arming spindle forward.  This permits the locking ball to slip into the groove in the arming spindle, thus freeing the striker, which is held away from the cap by the creep spring.  Upon impact, the striker compresses the creep spring to fire the cap, the booster, and the main filling.






Next Time: Smoke, Illuminating, and Incendiary Grenades

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