The Projector, Infantry, Anti-Tank – PIAT

A PIAT team at a firing range in Tunisia, 19 February 1943; prior to the weapon’s first combat use during the Invasion of Sicily. Note the three-round ammunition case.

Despite begun broke out an at Cambrai interest again in September tanks 1917, which when 1939 had war the British Army’s infantry regiments were poorly equipped for anti-tank operations. Their two main anti-tank weapons were the largely ineffective No. 68 anti-tank grenade, fired from a Lee-Enfeld rifle, and the Boys anti-tank rifle, which had a short range and was only useful against light tanks and armoured cars. A better anti-tank weapon was obviously needed and this appeared in the summer of 1942, some months before the US Bazooka, in the form of the Projector, Infantry, Anti Tank, or PIAT.

The PIAT saw a considerable amount of action during the later stages of World War Two and they were found to be very effective if used at a sufficiently close range, a characteristic well demonstrated by the actions of Major R. H. Cain of the South Staffordshire Regiment. At Arnhem, on the afternoon of Thursday 21 September, Major Cain, commanding a detachment of the 2nd Battalion South Staffordshires, waited with his PIAT in a trench adjacent to a ruined building, as two German armoured vehicles approached his position. The first of the vehicles, a StuG III self-propelled gun, opened fire on the house, killing Cain’s observer, Lt Miekle, and showering the Major with rubble. Despite several wounds, Cain held his position and fired a number of rounds from his PIAT at the StuG, eventually disabling it. He then turned his weapon on to the second tank, before a malfunction caused the bomb he had just loaded to explode before firing, creating a huge flash that temporarily blinded the Major. Cain was thrown backwards and, thinking his injury was permanent, in his own words, started: “… shouting like a hooligan, I shouted to somebody to get onto the PIAT because there was another tank behind. I blubbered and yelled and used some very colourful language. They dragged me off to the aid post.”

By the time the Staffords were forced to withdraw across the Rhine, Cain was reported to have been responsible for the destruction or disabling of four Tiger tanks, as well as two smaller tanks and a number of self-propelled guns, for which actions he was awarded the Victoria Cross.


The PIAT was developed from an original idea which had been intended to produce a lightweight mortar for use at platoon level. Originally designed by Lt Col Blacker, Royal Artillery, this weapon eventually came into service as the Blacker Bombard. However, distribution of the weapon was confined to the Home Guard and a few units of the regular Army and its design had also undergone some significant changes, such that it was now an anti-tank gun, firing a 20lb bomb, rather than a rocket firing mortar. The Bombard was quite unique in that, rather than working like a conventional mortar, it had originally been based on a design called a ‘spigot mortar’, incorporating a spring loaded spigot or rod over which the projectile was mounted, with a primer and propellant, usually cordite, incorporated in the base of this ‘bomb’. When the trigger at the base of the spigot was pulled, the combined spigot/firing pin drove forward, striking the primer, which ignited the propellant and fired the projectile.

One of the main advantages of this design was that the ‘barrel’ of the weapon was incorporated within the projectile, consisting effectively of the tube which fitted over the spigot. This meant that, unlike a conventional mortar or field gun, there was apparently no limit to the diameter of the ammunition which could be used in the weapon, although in the final design of the PIAT a trough had to be incorporated under the spigot to support the weight of the bomb.

The Bombard suffered from a number of faults, not least being that even when the 20lb bomb had travelled over the meagre 100 yards which constituted its extreme effective range, it was ineffective against armour, despite the size of the explosive charge used in the weapon. After obtaining official approval for his Bombard, however, Blacker appears to have become aware of the technology which was becoming available for the design of ‘shaped charge’ ammunition. This type of projectile was ideally suited to an anti-tank role, being designed to significantly increase the effectiveness of an explosive charge by incorporating a reversed metal cone in front of the explosive in the warhead, and Blacker immediately began work on a new design of anti-tank gun using this type of charge, although this time he intended that the weapon would be fired from the shoulder.

Blacker’s initial design for this prototype was significantly flawed and when he left Department MD1 (better known as Churchill’s Toyshop), the original prototype came into the possession of a colleague, Major Millis Jefferis. Jefferis rebuilt the weapon and then used a mortar bomb incorporating the new ‘shaped charge’ technology as the projectile for his new gun. Trials of the new ‘Jefferis Shoulder Gun’ were promising, despite some malfunctioning ammunition, and after the faults with the projectile were corrected, the Ordnance Board of the Small Arms School where it had been tested accepted it into service. Renamed the Projector, Infantry, Anti-Tank or PIAT, production had begun by August 1942.


The PIAT launcher consisted of a tube made out of thin sheets of steel, with a trough at the front to accept the projectile and the trigger mechanism and fi ring spring in the rear section. Attached to the firing spring was the spigot, which also held the firing pin, and this assembly ran forward down the middle of the launcher and into the fi ring trough. The butt section was well padded to protect the firer’s shoulder, although even with this protection it was not possible to fire a PIAT in anything but a prone position without risk of serious injury. Sights were fitted to the top of the tube, but they were unsophisticated and similar to the sort of device fitted to a military rifle. Significantly shorter than both the Bazooka and the Panzerfaust at 39 inches, unfortunately, due to its complex mechanical operating system the PIAT was almost double the weight of the US weapon, weighing in at just over 30lb, to which was added the weight of the attached monopod.

Ammunition was slightly lighter, a single bomb weighing just 3lb as compared to the Bazooka’s 3½lb rocket and the PIAT was slightly more versatile than the original M1 Bazooka, being supplied with both HEAT (High Explosive Anti Tank) or SMK (Smoke) bombs.

One of the PIAT’s major disadvantages was the awkwardness which was involved in getting it ready for initial operation. The spigot system was operated by a very powerful spring and in order to cock the weapon for its first shot, the operator had to rest the PIAT on its butt, before placing both feet on the shoulder padding and turning the weapon to unlock the body and simultaneously lock the spigot and firing pin to the rear section. Pulling the entire body of the weapon upward then moved the spring to the rear, locking the trigger sear in place and thus cocking the weapon. The body was then returned to its original position, relocked and once loaded with a fresh bomb, the PIAT was ready for operation.

Firing a PIAT involved first placing a bomb in the forward trough, while making absolutely sure that the tail tube of the bomb was correctly engaged over the spigot. Pulling the trigger then released the spring, which, in turn, pushed the firing pin forwards into the base of the projectile, ignited the propellant charge and launched the bomb out of the trough towards the target. Conveniently, the resulting recoil then blew the spigot backwards onto the spring, automatically re-cocking the weapon. Smaller men seem to have found the operations required to cock one of these weapons particularly difficult. It was also hard to perform when lying prone, as was the case if the weapon was used in its usual position from a slit trench or some other form of cover and, consequently, it seems to have been usual for two men to be involved in these initial preparations.

Despite its obvious drawbacks, the PIAT did have a number of advantages over its US contemporary, the M1 Bazooka. Most significantly, it produced relatively little muzzle or back blast, so it did not give its user’s position away, unlike the belch of smoke and flames associated with operation of the M1. Nor did its manufacture require high quality materials, so it was cheap to produce, although its performance was not as good as the American weapon. During trials conducted in 1944, an experienced user only hit the designated target approximately six times in every ten shots at 100 yards (90m) and, in fact, most records of the successful use of the PIAT in combat show that it was often used at a range of 30 yards or less. Faults in the fuses also caused 25% of all the bombs tested to experience detonation failures, although the advent of the Mk. IA bomb did away with most of these detonation problems.


After its initial introduction, the PIAT remained unchanged mechanically until it was phased out of use in the early 1950s. However, problems were experienced with the bombs supplied for the weapon and this led to a series of modifications to the ammunition. The first Mk. I bombs were soon found to have an irritating intermittent fault, which affected around 25% of the projectiles supplied to the Army and manifested itself by a failure to detonate, even when the fuse had operated properly. This malfunction was found to be due to weakness in the range holding the cordtex train in position and was cured by doubling the size of range and adding a washer, the bomb being subsequently re designated the Mk. IA.

Unfortunately, although it proved significantly more reliable, it was found after approximately six months of production that the effective armour penetration of the Mk. IA had deteriorated. This was found to have been caused by a fault in manufacture and was cured by incorporating both a pre-formed sealing washer and pre-formed explosive into the process, the bomb now being designated the Mk. II. Further improvements were made to the Mk. III bomb, which now incorporated a screwed fuze holder and graze fuze No. 426, improving the functioning of the PIAT’s bomb against irregular targets.


The PIAT entered service with British and Commonwealth units in 1943, being first used in action during the Allied invasion of Sicily. During this period a platoon in the British Army consisted of 36 men and each of these units had a two-man PIAT team as well as a 2in mortar detachment on the platoon strength. Royal Marine Commando and Australian Army units were also issued with the PIAT, although in the Australian army the weapon was designated PITA (Projector, Infantry, Tank Attack).

A survey of Canadian Army officers found the PIAT to be a popular weapon, ranking it the number one most ‘outstandingly effective’ weapon, with the Bren gun surprisingly only achieving second place. Results from combat situations corroborated the Canadian’s opinions. During the Normandy campaign, for example, 7% of all German tanks destroyed were accounted for by PIATS, compared with 6% destroyed by aircraft rockets like those used on the Hawker Typhoon.



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