page_title: Mortar (weapon)
section_title: Spigot mortar
hierarchical_section_title: Mortar (weapon) / Types / Spigot mortar
caption_attribution_description: English: Men of the Saxmundham Home Guard prepare to fire a 'Blacker Bombard' during training with War Office instructors, 30 July 1941. The weapon was a 29mm spigot mortar, designed by a Lieutenant Colonel V V S Blacker, and could fire a 20lb bomb some 900yds.
context_page_description: A mortar is usually a simple, lightweight, man-portable, muzzle-loaded weapon, consisting of a smooth-bore metal tube fixed to a base plate with a lightweight bipod mount and a sight. They launch explosive shells in high-arcing ballistic trajectories. Mortars are typically used as indirect fire weapons for close fire support with a variety of ammunition.
context_section_description: Spigot mortars, a particular type of mortar, consist mainly of a solid rod or spigot, onto which a hollow tube in the projectile fits—inverting the normal tube-mortar arrangement. At the top of the tube in the projectile, a cavity contains propellant, such as cordite. There is usually a trigger mechanism built into the base of the spigot, with a long firing pin running up the length of the spigot activating a primer inside the projectile and firing the propellant charge.
  The advantage of a spigot mortar is that the firing unit (baseplate and spigot) is smaller and lighter than a conventional tube mortar of equivalent payload and range. It is also somewhat simpler to manufacture. Further, most spigot mortars have no barrel in the conventional sense, which means ammunition of almost any weight and diameter can be fired from the same mortar.
  The disadvantage is that while most mortar bombs have a streamlined shape towards the back that fits a spigot mortar application well, using that space for the spigot mortar tube takes volume and mass away from the payload of the projectile. If a soldier is carrying only a few projectiles, the projectile weight disadvantage is not significant. However, the weight of a large quantity of the heavier and more complex spigot projectiles offsets the weight saved due to the spigot mortar being lighter than a conventional mortar.
  A near-silent mortar can operate using the spigot principle. Each round has a close-fitting sliding plug in the tube that fits over the spigot. When the round is fired, the projectile is pushed off the spigot, but before the plug clears the spigot it is caught by a constriction at the base of the tube. This traps the gases from the propelling charge and hence the sound of the firing. After World War II the Belgium Fly-K silent spigot mortar was accepted into French service as the TN-8111.
  Spigot mortars are generally out of favor in modern usage, replaced by small conventional mortars. Military applications of spigot mortars include:
  The 290 mm petard mortar used on the Churchill AVRE by Britain in World War II.
  The 320 mm Type 98 mortar used by Japan in World War II to some psychological effect in the battles of Iwo Jima and Okinawa
  Anti-tank launchers
  The Blacker Bombard and PIAT anti-tank launcher used by Britain in World War II utilised a spigot mortar type of launcher.
  Anti-submarine launchers
  The Hedgehog launcher, used from the deck of a ship, used 24 spigot mortars which fired a diamond pattern of anti-submarine projectiles into the sea ahead of the ship. A sinking projectile detonated if it struck a submarine, and the pattern was such that any submarine partly in the landing zone of the projectiles would be struck one or more times.
  Non-military applications include the use of small-calibre spigot mortars to launch lightweight, low-velocity foam dummy targets used for training retriever dogs for bird hunting. Extremely simple launchers use a separate small primer cap as the sole propellant (similar or identical to the cartridges used in industrial nail guns).
caption: A Blacker Bombard during training
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