The PIAT (Projector, Infantry, Anti-Tank) known as the Jefferis Shoulder Gun during development, was a crew-served portable anti-tank system developed by British Major Millis Jefferis in 1941 to replace the obsolete Boys anti-tank rifle and provide a weapon with a greater effective range than the No. 68 anti-tank rifle grenade. An order for 100,000 launchers and 5 million rounds of ammunition was placed in 1942, and it was first issued to field units in North Africa in January 1943. The ammunition requirement was later increased to 13.3 million rounds.
Design[]
It was a scaled-down version of the carriage-mounted Blacker Bombard: Lieutenant Colonel Stewart Blacker had previously tried to produce such a weapon (the "Baby Bombard"), but it was only with the introduction of hollow charge technology that the system found an effective projectile.
Functionally the PIAT is a very unusual example of a spigot mortar (while it uses a mortar mechanism, the weapon itself is not a mortar), using a 12-pound spring-fired striking rod fired to ignite a propelling charge in the base of the projectile, which would then fire it from the loading tray at the front of the weapon. The striker was initially cocked by pulling down on the padded buttplate, rotating it and sliding it back forward: this was a strenuous operation as the spring tension was around two hundred pounds, and gunners would typically perform it lying down, bracing the buttplate with both feet and pulling the body of the launcher upwards. This was notoriously difficult for soldiers of shorter stature.
In theory, if the buttplate was properly braced against the shoulder the weapon would self-cock on firing from the recoil force applied to the spigot assembly, but in practice the assembly often failed to catch in the rearward position, requiring manual cocking after each shot. The vicious recoil of the system resulted in British troops joking that a soldier deserved the Victoria Cross just for firing the weapon. Average rate of aimed fire was 2-5 rounds per minute for a trained crew.
This unusual system removed the need for a conventional barrel: the projectile instead sits in a tray at the front of the weapon, loaded from above and with a locking clip to retain the projectile by the tail so it does not fall out of the weapon if moved. This therefore removed the need to manufacture the weapon to handle internal pressure. The result was that the PIAT could be produced to fairly loose manufacturing tolerances and did not require high-quality materials, a major benefit at that point in the war.
Ammunition[]
The ammunition (referred to as "bombs" by British forces, the same term used for mortar projectiles) consisted of a bulbous hollow-charge warhead with a projecting fuze. From the base of the warhead extended a long, hollow rod to which a stabilising cylindrical tail assembly was attached. The projectile was primed prior to firing with a ballistite propelling cartridge inserted into the tail. Rounds were also carried with the fuze removed, kept in a small container attached to the bomb's tail with a spring clip. To arm the bomb, the fuze was removed from the container and the "thimble" tip of the detonator assembly was removed, which exposed a transit plug in the fuze well: this was removed, replaced with the fuze, and the thimble replaced. Soldiers were instructed to retain the transit plug in the fuze container, as this process could be reversed to unfuze the bomb if it was not required.
Ammunition was issued in thick cardboard protective sleeves, usually packaged in sets of three. Three-tube sets were bound together with metal straps and fitted with a webbing carrying handle.
Early production projectiles had issues that reduced their effectiveness. The original Mk I rounds sometimes failed to explode even though their fuze had detonated: this was traced to a fault in the design of the cordtex "detonation train" that was supposed to carry the spark from the fuze to the explosive liner. The detonation train was redesigned and the improved version became known as the Mk IA. After six months of production, it was noted that performance against armour was not to spec, and this was traced to a faulty production process which would often result in the hollow charge's explosive liner detaching from the forming cone during transit, reducing the warhead's penetration capability substantially (less than 75mm at zero degrees as opposed to the expected 100mm). The Mk II bomb featured a redesigned liner attachment process to mitigate this.
In addition, like early Bazooka rounds, PIAT projectiles could fail to detonate if they did not strike square-on, as the projecting fuze would skip off the target's armour or even be torn off the bomb by the force of a glancing impact. The Mk III round addressed this with a redesigned fuze holder and a switch from a No. 425 impact fuze to a No. 426 graze fuze: the latter was triggered by deceleration of the bomb rather than crushing of the nose probe. In addition, this model switched from the original Nobel 808 plastic explosive filler to TNT.
Another key issue as firing ranges grew shorter was that on detonation, the projectile's tail assembly would sometimes detach from the bomb and be ejected in the direction it had been fired from, with potentially lethal results for the gun crew at short range. This was addressed in the final Mk IV design in July 1944, which increased the structural strength of the projectile overall and the tail assembly in particular.
A bomb's type can be determined to an extent by external markings: Mk I, IA and II projectiles have a green horizontal band on the warhead between two yellow, with "808" stamped on the green band and red "X" markings near the nose. Mk III and IV bombs instead have a blue band between two yellow which is stamped "TNT," and a red circle that surrounds the fuze probe.
Three other types of projectile existed with different markings, all used for training: inert bombs were painted black with a yellow band with "INERT" stamped just below it. This variant had ballast weight instead of a warhead but could accept a live propelling cartridge: it was single-use, not built strongly enough to survive repeat firing. The drill bomb had no stripe and the word "DRILL" stencilled twice on opposite sides of the warhead, and also had "DRILL" marked on the fuze holder. This type could not accept a propelling cartridge and was used only for manual-of-arms drills. Finally, the "practice bomb" was a device which did not even resemble any other type of projectile for the weapon, instead looking more like a small stick grenade. This was used with a feed tray insert to allow simulated loading and firing of the weapon in training. Being solidly built from thick steel pipe, this type, unlike the inert bomb, could be recovered and fired multiple times, thought this came at the cost of having slightly different ballistics to a real projectile.
Performance[]
The PIAT could throw a two and a half pound projectile up to 330 yards when firing in a low arc, and could hit a point target at 109 yards: against armour, the range was much lower, around 40 yards. Canadian forces in Italy also had some success employing the PIAT as a crude mortar by bracing the stock against the ground: as this was not an official function of the system, there are no figures for its range when used in this way.
Due to the design issues with ammunition outlined above, in Sicily around 25% of shots fired failed to explode. In addition, as the projectile only received alignment guidance from the spigot pushing into it, it was somewhat inaccurate, with tests after the invasion of Sicily showing only a 60% first-shot hit rate against a crossing tank-sized target at 100 yards: the fact that over a third of the gun's weight changed ends an instant before firing did not help matters. Being a single-stage HEAT warhead, it also suffered a decrease in performance as German tanks began to employ standoff side-skirts.
The heavy weight, large size and awkward shape of the PIAT was compounded somewhat by the fact that no sling designed for it was ever issued, despite the weapon being factory-fitted with a pair of sling swivels. PIAT gunners were usually issued rifle slings, but would often scrounge slings for Bren guns, finding them more comfortable.
Use[]
The PIAT was the principle anti-tank weapon of British Empire and Commonwealth forces from its adoption to the end of the Second World War, and served in every theatre where Commonwealth forces were present. Despite its shortcomings, it proved to be more reliable than early Bazooka variants and at the time of adoption could potentially knock out any German armoured vehicle in service, as well as being useful in assaulting structures. Due to its small firing signature (only a puff of smoke from the propelling charge detonating), PIAT teams proved difficult to locate in built-up areas, and the lack of backblast from the weapon meant they could fire the PIAT from enclosed spaces without time-consuming preparations.
As well as being used by the forces of the British Commonwealth, the PIAT was supplied extensively to partisan groups fighting in occupied Europe, and 1,000 PIATs and 100,000 rounds of ammunition were supplied to the Soviet Union as part of lend-lease. The PIAT was retired from British service in the 1950s, being phased out in favour of the ENERGA rifle grenade and the M20 "Super Bazooka." Australian troops briefly used the PIAT during the early stages of their involvement in the Korean War, though they too quickly adopted the M20.
Israeli forces used PIATs against Arab armour during the Israeli War of Independence, and one of the last known uses of the weapon in a major conflict was by French and Việt Minh forces during the First Indochina War.
