Category Archives: Ordnance

20mm Vulcan Cannon Ballast Round

Last year we looked at a 30mm Aden Ballast round here. Since then I have been able to pick up a second ballast round, but this time for a 20mm Vulcan cannon:imageIn appearance this is very much like the other ballast round, being made of a solid piece of cast white metal. The shape is identical to a live Vulcan round with an extractor groove at the bottom:imageAnd the top having the shape of the actual projectile:imageThe weight of the round is identical to that of a real Vulcan round, being used to safely test the weapon and its timing, allowing adjustments to be made on the ground in a controlled environment. Here we see a dismounted Vulcan with a belt of this ammunition:PGU-27-AB-20-102mm-ammunition-m-61-vulcanThe Vulcan is a six barrelled 20mm rotary cannon used on fixed wing aircraft. It was developed in the United States but saw service with the British on aircraft such as the F-4 Phantom. The need for the weapon came out of experience in the Second World War and the realisation that with the speeds jets were becoming capable of, there would only be a split second when rounds would actually connect with their target. This therefore required a weapon with a very high rate of firepower and a round that had enough mass that a few strikes would destroy a plane. 20mm had proved effective in the Second World War and by pairing this with an electrically driven Gatling type of gun extremely high rates of fire could be achieved, in the case of the Vulcan 6,000 rounds a minute. The new cannon was designated the M61 by the US.Vulcan1Each of the cannon’s six barrels fires once in turn during each revolution of the barrel cluster. The multiple barrels provide both a very high rate of fire—around 100 rounds per second—and contribute to prolonged weapon life by minimizing barrel erosion and heat generation. Mean time between jams or failures is in excess of 10,000 rounds, making it an extremely reliable weapon. Most aircraft versions of the M61 are hydraulically driven and electrically primed. The gun rotor, barrel assembly and ammunition feed system are rotated by a hydraulic drive motor through a system of flexible drive shafts. The round is fired by an electric priming system where an electric current from a firing lead passes through the firing pin to the primer as each round is rotated into the firing position.

One RAF Phantom pilot explains the advantages of the cannon over radar guided missiles:

Being unguided, bullets are not susceptible to Electronic Counter Measures (ECM – although the radar used to aim the gun, of course, is) and the gun has no technical minimum range, although there are some practical reasons (e.g. arming of high explosive rounds) why you wouldn’t choose to fire from too close to the target. Also some pilots didn’t like the idea of large aircraft blowing up in their face. In my day, the closer you got to a target, the bigger it looked in the windscreen making it easier to hit! I say ‘A kill’s a kill!!

An RAF Phantom carried 640 rounds for its Vulcan canon and it seems to have been a popular weapon amongst aircrews, combining high rates of fire with impressive hitting abilities. My thanks go to Gary Hancock for his help in identifying this round.

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120mm Chieftain HESH Round Transit Tube

It is perhaps unlikely that I will ever have the funds or space to be able to add a tank to my collection (plus I imagine my wife would have a few choice words to say if I did). Small items of militaria related to armour are available though and tonight we are looking at the plastic transit case for a Chieftain 120mm HESH shell:imageThe Chieftain was Britain’s main battle tank throughout much of the Cold War and had a 120mm rifled main gun. Britain used a variety of shells with this gun including HESH, which stands for High Explosive, Squash Head.

HESH rounds are thin metal shells filled with plastic explosive and a delayed-action base fuze. The plastic explosive is “squashed” against the surface of the target on impact and spreads out to form a disc or “pat” of explosive. The base fuze detonates the explosive milliseconds later, creating a shock wave that, owing to its large surface area and direct contact with the target, is transmitted through the material. In the case of the metal armour of a tank, the compression shock wave is conducted through the armour to the point where it reaches the metal/air interface (the hollow crew compartment), where some of the energy is reflected as a tension wave. At the point where the compression and tension waves intersect, a high-stress zone is created in the metal, causing pieces of steel to be projected off the interior wall at high velocity. This fragmentation by blast wave is known as spalling, with the fragments themselves known as spall. The spall travels through the interior of the vehicle at high velocity, killing or injuring the crew, damaging equipment, and/or igniting ammunition and fuel. Unlike high-explosive anti-tank (HEAT) rounds, which are shaped charge ammunition, HESH shells are not specifically designed to perforate the armour of main battle tanks. HESH shells rely instead on the transmission of the shock wave through the solid steel armour.lc-120-HESH-L31A2HESH ammunition has good general purpose use, being effective against most targets, though the round is generally used at relatively low velocities because high velocity excessively disperses the pat of explosive. While only effective against tanks without spaced armour or spall liners, the round is still highly favoured for combat demolition purposes. The flattened high-velocity explosive pat is capable of destroying concrete constructions much faster than a HEAT round (which is designed for armour penetration), and without the dangerous fragmentation of a traditional high-explosive (HE) fragmentation round.CR3_thumb_png_1bffb6a288cd7b02814b48cbb0570342These rounds were delivered in individual plastic transit tubes, and two of these were packed inside a metal ammunition box. The plastic container has a screw on lid with a rubber seal to prevent any moisture from entering inside. A wire loop handle is fitted to the top to make them easier to carry:imageSmall holes are fitted around the outside of the lid and main tube to allow a piece of wire to be fitted as a tamper prevention measure:imageThe front of the tube has a pair of labels attached, firstly we have a diamond shaped MOD explosives label, sadly now starting to peel off:imageAnd a large contents label that shows the tube contained a 120mm HESH round, L31A7. The round was manufactured in January 1969, whilst the fuze was produced in December 1968:imageThe tube itself has the date of manufacture moulded into the base, here for 1967:imageThese tubes do appear from time to time, but as they were reused a number of times it is quite nice to get one with labels for as early as 1969, this example was clearly only ever used once and never refilled.Chieftain_Tank_(9628802829)

Jet Engine Starter Cartridge

Early jet engines needed a way to turn the motor over to start the engine going. Many propeller driven aircraft had relied on a man swinging the propeller to turn the engine to kick it into life. This was obviously not an option with a jet engine so a large blank starter cartridge was used. Made of brass, this cartridge looks very much like an artillery shell:imageIt was in effect a large blank cartridge and the gasses from this cartridge expanded and turned the engine over allowing it to start. The top of the case has bent over lips and originally when it was full these would have held a large disc made of a material that would have been consumed by the explosion, such as cardboard:imageThe base of the cartridge is marked up and we can tell this is an Electric Starter Cartridge No9 Mk I and was manufactured in 1952. The ‘K’ indicates it was produced by Kynoch:imageThese cartridges were used on a number of early RAF jets including the Canberra and the Hunter. One American technician who worked on the Canberra bomber recalls using these cartridges:

Tech question: yes, the starter cartridge in the older marks of Canberra was just a huge shotgun shell, albeit without the shot. There was an explosive release of gases which was channelled to the turbine to wind the thing up. The earliest marks B2, T4, TT18 had only 1 fitted per engine, so, after a failed start, it would take several minutes for the area to cool enough for the cartridge to be replaced, often resulting in a delay of 20 minutes or more. 6

The latter (early) marks, PR7, E15, T17, T22 had 3 per engine, 2 as spares. The last mark, PR9, used a really nasty explosive fuel called AVPIN, which was volatile in the extreme. One of our jeeps carrying the stuff through a small town, fortunately in an unpopulated area, caught fire spontaneously, the driver bailed, and the resultant conflagration melted the concrete of the sidewalk. You can imagine the effect this had on the local populous – we were thereafter banned from transporting it through residential areas.

The explosion from the starter cartridge was impressive: 4-foot flames would leap from 3 vents in the engine casing, the whole area would be wreathed in pungent cordite smoke, and pilot and supervising technician would watch the engine and each other nervously in case of engine fire. In 3 years, I only had to evacuate once because of a suspected fire, which turned out to be a false alarm. However, you can imagine that when the plane was fully fuelled, we were out of there in a flash and up and running! untitled
The gas release should take the engine up to about 2000 RPM, which was enough to energize the igniters and allow the engine to work with the start inertia to get it up to normal idling RPM (I forget the figure). The main thing you were watching at this stage was either for an internal fire, in which case the EGT gages would leap off the scale, or compressor surge, usually accompanied by a lot of popping and banging. In both cases, the actions would be the same: throttle closed, HP cock closed, LP pump off; for a fire of course, additional actions would be fire extinguisher shot through the engine (only 1 available) and evacuate (run for the hills!).

Mk V .303 Blank

Happy Empire Day! If you have not already checked out our sister site ‘British Empire Uniforms’ on Facebook please, take a look. There are plenty of period photographs and reconstructions of uniforms from around the Empire in the Interwar and Second World War periods.

Like all countries, the British made extensive use of blank ammunition in training. The .303 round had a number of different types of blank ammunition before settling on the Mk V. in 1894 when cordite was introduced. This round was to remain in service 1957 when the Mk 9 blank was introduced that had a nitrocellulose propellant. Tonight we are taking a closer look at the ubiquitous Mk V cordite blank and we have two different examples:imageThe round on the right is, I believe, a WW1 blank as it came from a WW1 charger of WW1 dated spent rounds so it seems logical to assume it is of that vintage. The round on the left has a 1942 date stamp so is most likely a WW2 blank round. The reason I am being cautious with the dates is that these blanks were often made form cartridge cases that were rejected as not being suitable for ball ammunition, but were still good enough to be converted to blanks. This means the head stamps do not necessarily correspond to the blank itself as they would have been added before the case was relegated to use as a blank. The case heads of these two examples therefore may only tell us when the case itself was manufactured, not when it was converted into a blank:imageThe round on the right is dated 1942 and was manufactured for a Mk VII ball round by Radway Green, that on the left has the ‘K’ for Kynoch. These rounds are Berdan primed rather than having the earlier Boxer primers and the blank itself used 10 grains of sliced cordite. The neck of the case was closed with a rosette crimp:imageBlanks were used extensively for training, and rounds that had been dropped by accident provided great, if dangerous, fun to local children as recalled by Raymond McElvenney:

During the war, these old building were used by the army for training purposes. To make the exercises more realistic, they fired blanks from their guns and there was much banging from large firework things called ‘thunder flashes’…

After the soldiers had gone, we went around the building collecting the spent cartridges up. We also found a number of unfired bullets, so we put them in a crack in the wall. We found a piece of wood with a nail in it; we placed the nail against the bottom of the bullet and hit it with a brick causing the bullet to explode. We thought this was great fun.

In this instance I think the boys actually found unfired blanks, despite the author’s reference to bullets!

5.56mm Ball Round

When the SA80 rifle was introduced a whole new calibre of cartridge entered British service, the 5.56mm NATO round. This round had been produced as prototype ammunition for at least five years when the SA80 was rolled out in 1985 but large scale British manufacture had not yet started so initial ammunition had to be sourced from overseas. The first British produced rounds began to be manufactured in 1984 but it took time for production to ramp up. The new cartridge was produced at the factories at Radway Green and was of a conventional design with a brass casing:imageLike all modern ammunition this round is rimless and has an extractor groove cut into the base:imageThe bullet itself weighs 4.0 grams and is projected using 1.52 grams of propellant, either NNN (cut tubular) or later nitrocellulose (cut tubular):imageThis particular round was produced in 1993 by Radway Green, as can be seen but the headstamp:imageI suspect that this inert round has actually been assembled from a fired tracer round, rather than a true ball cartridge as the ball rounds had the designation L2A1 and L2A2 when in service and this is marked as L1A1.

When the new ammunition was issued, it warranted a special explanation in the publicity material for the new SA80 rifle:

Ammunition

The ammunition in the new standard 5.56mm calibre meets the performance requirements of both the UK and NATO. In meeting operational requirements it is fully effective up to a range of 1000 metres as generally required in infantry operations. To meet the stringent standards of the UK ordnance Board all rounds are manufactured under high quality control conditions. A variety of natures are available, i.e. Ball, Tracer, Blank Drill and Low Power Training.

An important feature of the ammunition is that it is less than half the weight of the alternative standard NATO 7.62mm ammunition. This enables more rounds to be carried by an infantryman thereby extending logistic capability and operational effectiveness.

The relative merits of 5.56mm versus 7.6nmm ammunition have been debated since the introduction of the smaller calibre. The 5.56mm round is lighter and easier to fire more accurately, but lacks the range and power of a 7.62mm which has remained in service for the GPMG so the army has ended up with two calibres of ammunition. It was felt most combat would be at short range so the lower power would not be an issue and generally this has proved to be the case, however in Afghanistan troops found themselves up against insurgents equipped with old fashioned rifles who could engage targets from well outside the range of the British infantryman’s weapon. As is so often the case, there is no perfect cartridge size and there are good arguments on both sides of the debate, what is clear is that despite research into intermediate cartridges the 5.56mm calibre is here to stay in the short to medium term.

30mm Aden Practice Round Shell Casing

The 30mm Aden cannon was a very successful post war aircraft gun, and we covered much of its history when we looked at an example of the links used to join cartridges here. Tonight we have the casing from one of those rounds to look at:imageSadly this is just the casing and is missing the head, but it can be seen that it is a brass case, with a large extraction groove at the base. The primer has been struck as one would expect from a fired round:imageThe markings for the Aden round are marked around the circumference of the case, rather than on the base:imageThe markings indicate that this is a 30mm practice round, manufactured by Radway Green in 1973. I have found this very useful diagram that shows what the various markings mean:GAERGHRE_croppedThe empty brass casings were ejected out of the underside of the aircraft, falling to the ground below. This could sometimes be a little disconcerting to friendly forces on the ground:

Just below its ‘shoulders’, where the leading edge of the wings meets the fuselage, the hunter had two large bulges called Sabrinas (they were named after a popular actress of the time who also had two large bulges just below her shoulders). The Sabrinas were there to accommodate the empty links from the 30mm ammunition belts that fed the Aden cannon. Simply letting the link belts shoot out of a slot behind the aircraft’s nose might have allowed the belts to foul the aircraft’s control surfaces. There were no such fears, however, about the spent shell cases. They were ejected from two holes immediately above each Sabrina- and even a quick three-second burst meant that at least 240 30mm brass shell cases came tumbling down. If just one of those caught you on the head it would be enough to lay you out. As soon as the brass rain started, we were under cover with Alfie quicker than you could day ‘concussion’…

.303 Blank Ammunition Packaging

Like most other armies, Britain has long used black ammunition in training to provide realistic battle noise without risk of live rounds. In 1955 the British introduced a new blank round for the .303 rifle and machine guns still in service. This new round was externally identical to previous ammunition but now used nitrocellulose rather than cordite as a propellant. This excellent British Small Arms Ammunition site explains:

It is something of a mystery why the L Mark 9z blank was approved, since it is in all intents and purposes simply the nitrocellulose version of the Blank L Mark 5, the L Mark 5z which had been approved in 1928.

“Cartridge S.A. Blank .303 inch L Mark 9z” was approved to design DD/L/14006 in March 1955 and shown in LoC Paragraph C.7827 dated January 1957.

The case was Berdan primed and had the neck closed with a rosette crimp. cases were newly made and usually included the code “L9Z” but considerable numbers were issued with no headstamp.

The charge was 14 grains of ballistite or nitrocellulose covered with a single wad.

Tonight however we are not looking at the blank itself, but the box it was issued in:imageBlanks came packaged in brown cardboard boxes which held twenty rounds- enough for four chargers. Twenty rounds also meant that two boxes would fill three Bren magazines. A green paper label is pasted around the outside detailing the contents and a date has been stamped on indicating that the original contents were packaged by Radway Green on 17th October 1956:imageThe information is repeated on the ends of the box as well so that even if stood up in an ammunition box it is still easy to identify exactly what sort of ammunition the cardboard packet contains:imageThese boxes were essentially disposable and most were simply thrown away. This means these humble cardboard boxes have become increasingly collectible. Post war examples such as this are still fairly overlooked but wartime boxes are becoming scarcer and commanding good money for what essentially is just a piece of discarded packaging!