Spigot Mortar

The Blacker Bombard (or 29mm Spigot Mortar) was a spigot gun – i.e. the projectile fitted onto a steel rod, or spigot, instead of into a barrel. The weapon consisted of an alloy steel rod on which the bomb was loaded and also contained the firing pin. The steel rod controlled the direction of fire. To protect the crew against blast when the weapon was fired, a steel casing was fitted around the rod.

Sights for the weapon consisted of an aperture back sight and bead foresight. The foresight had aiming off beads to allow for moving targets at varying speeds. The gun was aimed as follows:

• Moving targets – set elevation to 200 yards then set actual range on ranging drum (which moved the sight relative to the spigot).

• Stationary targets – set range drum to 200 yards and then set actual range on elevation arm.

Right - Blacker Bombard on
portable mounting

The gun fired a 20 lb anti-tank bomb or 14 lb H.E (anti-personnel bomb). Ranges and rates of fire were:

• Anti-tank round – max range 450 yards; most effective at 75-200 yards; max rate of fire 12 rounds per minute (normal rate of fire 6 rounds per minute)

• Anti personnel round (H.E round) – max range 950 yards; max rate of fire 15 rounds per minute (normal rate of fire 8 rounds per minute)

The weapon could be fired from either a portable mounting (four legs fitted with ‘spades’ for normal ground and driven in ‘pickets’ for soft ground) or a fixed concrete pedestal, set into a circular trench. It should be noted that the portable mounting could not be adapted to ground conditions meaning that a relatively flat surface had to be selected.

  Above left: Saxmundham Suffolk HG receiving a demonstration of the Blackard Bombard on the portable mounting.
  Above right: Example of Blackard Bombard mounted on fixed concrete pedestal, set in circular trench.

Tactical Handling:

Anti-tank role:

As the bombard had a short range and slow rate of fire compared to tank weapons, it was essential to employ the weapon as an ambush weapon. If possible it should get off its first shot at a pre-registered range and preferably at a stationary target before the enemy vehicle could engage it. The following principles were to be observed:

• It should cover approaches to the position

• It should be sited to a flank a tank obstacle or road block

• It should be sited to fire on enemy vehicles forced to halt by a road block or obstacle

• Positions should be well camouflaged –essential as road blocks / obstacles were almost impossible to hide and enemy reconnaissance would search for covering weapons

• Dummy positions should be constructed (any old piece of drainpipe to simulate the casing and an old piece of linoleum for the shield were suggested for use as camouflage)

• Alternative positions should be constructed (at least 80 yards apart)

• Ranging points to be set out and the crew trained to hold fire until the target reached a ranging point.

  Above: Camouflaging the Blackard Bombard

Anti-personnel role:

In this role the Bombard acted as an effective mortar. With a high trajectory, it could operate to deliver indirect fire on likely targets (e.g. enemy forming up points or machine gun / mortar locations). If sited in an anti-tank role it was NOT to be given an anti-personnel role. However if sited for an anti-personnel role, the crew should be expected to deal with armoured vehicles if necessary.

The weapon dismantled into seven main loads and could therefore be manhandled over short distances by its crew. An experienced crew could bring the gun into action one minute after its arrival at its new location.

The gun was introduced in 1941 (having originally been rejected in the 1930’s) and became a key weapon in Home Guard Defence schemes for Defended Places / Hold up Villages. It was also issued to most of Suffolk’s Emergency Coastal Batteries, examples still remaining at Minsmere and Sizewell Batteries.

A.E Patrick recalls the spigot gun during his time serving with the Bungay Home Guard. He notes an almost continuous training in the weapon which he recalls as being vey cumbersome, suitable only for younger men to handle. He was able to escape further training for this weapon when teams were selected for demonstration shoots at Lakenheath. He does however note that ‘in the hands of a good man a bomb could be sent over 600 yards accurately and make a mess of whatever it hit.'


Home Guard Instruction No 51 – Part IV: The Organization of Home Guard Defence, GHQ Home Forces 1943
29mm Spigot Mortar – Training Instructions (Provisional), WO, 1941
A Story of Bungay’s Home Guard, A.E Patrick, 1944, SRO


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