The 2B25: Russia’s Silent Spigot Mortar

Recently there have been a number of defence media articles about Russia’s new ‘silent’ mortar. It’s often described as cutting edge technology but in reality it’s based on technology over 100 years old. 

The Russian 2B25 82mm mortar is in fact a spigot mortar. What is a spigot mortar? Unlike a conventional mortar which uses gravity acting on the bomb dropped into the tube striking the anvil or striker at the base of the tube detonating the propellant cartridge in the bomb and launching the mortar bomb. A spigot mortar alters this principle, instead using a spigot or metal rod onto which a bomb with a hollow tail is placed. The bomb’s tail then becomes the element which contains the pressure from the detonated propellant charge rather than the tube as in a conventional mortar. The 2B25’s bomb has a plug at at the base of the propellant cartridge which when fired is pushed down the bomb’s tail tube by the expanding propellant gases – essentially acting as a piston. The plug is prevented from leaving the tube by a constriction at the tube’s end. This captures the gases and reduces the report of the mortar.

The 2B25 82mm Mortar (CRI Burevestnik/Russian Army)

Perhaps the most famous spigot mortars are the Blacker Bombard and PIAT (Projector, Infantry, Anti-Tank) of world war two. I wrote a book about the PIAT a couple of years ago so the 2B25 really interests me as a niche application of the same technology!

Spigot mortars have a number of benefits and drawbacks which set them apart from conventional mortars, including a shorter range and slower rate of fire than conventional mortars, but the advantages primarily seized upon is their reduced sound signature and lighter weight. The ignition of the propellant cartridge against the spigot, inside the bomb’s tail tube removes visible flash and is much quieter than a conventional mortar which. The 2B25 optimises this by enclosing the bomb inside a light weight tube to further reduce the visual and audio signatures of the weapon firing even further.

Why is this important and why are ‘silent’ mortars useful? With a reduced signature on the battlefield the chances of effective counter-battery fire are reduced enabling the mortar fire to be more effective and sustained. The developers claim that the 2B25 is about as loud as AK fitted with a PBS-1 suppressor, about 135db, substantially quieter than a standard mortar.

The patent for the 2B25’s bomb, filed in August 2011 and published in February 2013, states:

“proposed shell comprises main part and tail. Tail case accommodates propellant charge and combination piston with initiator. Shell is composed of detachable sealed screw assembly of tail and main part. Tail is furnished with fin. Tail charge chamber accommodates multi-section propellant to be implemented in various versions.”

Patent diagram of the 2B25’s self-contained piston bomb (Russian Patent #2494337)

The 2B25 first began to appear in western media back in 2018 but the design dates back to at least the early 2010s. Developed by the central research institute Burevestnik, it is manned by a two man team and can be transported in a backpack. Officially released data for the mortar suggests it has a maximum range of 1,200 metres with a rate of fire of perhaps 15 rounds per minute. It is reportedly equipped with a standard MPM-44M optical mortar sight.

The mortar appears to be of a fixed spigot design with a firing pin running inside the spigot. This means that unlike the PIAT the 2B25’s spigot does not move. Once the bomb is slid into the mortar tube, down onto the spigot, the operator pulls a handle at the base of the weapon downwards to cock the weapon and then pushing it up to fire it. 

The 2B25 82mm Mortar (CRI Burevestnik)

The mortar’s baseplate is said to be made of an aluminium alloy with the whole weapon weighing 13kg or 28.6lbs. The mortar’s 3VO35 bomb itself weights 3.3kg and has a 1.9kg warhead.

Both Russian and western media reports have stated that the weapon has been delivered to the Russian armed forces with some suggesting it was in use by “special-purpose units”, possibly Spetsnaz 

The 2B25 certainly isn’t the only modern spigot mortar in service, others include the Fly-K from Rheinmetall. Personally, I find it fascinating that spigot-based weapons still have a place on the battlefield, albeit a niche one.


If you enjoyed this video and article please consider supporting our work here. We have some great perks available for Patreon Supporters – including custom stickers and early access to videos! Thank you for your support!


Bibliography:

82mm 2B25 Mortar, CRI Burevstnik, (source)

Mortar Silent Shot, Russian Patent, RU2494337, 16 Aug. 2011, (source)

Mortar 2B25 “Gall” No noise and flash, TopWar, 26 Sept. 2018, (source)

Advanced Silent Mortars Start Arriving for Russian Army, Tass, 7 May 2019, (source)

Russian-made 2B25 “Gull” Silent Mortar will be Modernized in the Imminent Future, Army Recognition, 13 Nov. 2015, (source)

Russian Commandos Are Getting “Silent” Mortars, The Drive, 7 Sept. 2018, (source)

Footage:

Silent Killer: Test Footage of the Latest Mortar for Special Forces, Zvezda, 25 Dec. 2015, (source)

2B25 Silent Mortar, Rosoboronexport, 24 Nov. 2021, (source)

82mm Mortar Silent 2B25, Russian TV Report, 27 Feb. 2014, (source)

Home Guard Improvised Incendiary Weapon

On the 14th May 1940, the British Government announced the formation of the Local Defence Volunteers. By the summer of 1940 nearly 1.5 million men had volunteered to serve. The force was later renamed the Home Guard in July 1940 but remained under-equipped throughout the summer of 1940. Many of the newly raised militia units had just ‘LDV’ arm bands, some civilian firearms and improvised weapons, as uniforms and service weapons were in short supply.

I recently came across a really interesting piece of footage showing a Hampshire Home Guard unit training with an ‘incendiary weapon’. With few heavy weapons available during 1940, some Home Guard units improvised. This remarkable original colour footage appears to show a reasonably effective incendiary weapon of some sort. But beyond what we can see we know very little about the weapon.

The footage shows a battery of five launchers, each seemingly with a 3 man crew. One man aiming, another loading and another firing. The footage is undated but from their arm bands we can see that the men are Home Guard so definitely post July 1940. The men also appear to be quite well equipped with caps, denim trousers and blouses and belts. No webbing is seen but we can potentially date the footage to between late 1940 and mid-1941.

Crews dash to their launchers. Note the rifle stock-shaped pieces to the side of the weapons which appear to have been used to aim the launcher

The incendiary weapon itself is extremely intriguing! I haven’t seen a similar weapon before and I couldn’t find any direct reference to it in the available original documents, newspapers or photos. The footage comes from the Wessex Film and Sound Archive, it is described as showing Home Guard men from Swanmore, a rural village in Hampshire, demonstrating the weapons. Before the incendiary weapon is demonstrated we see a company sized force of Home Guard parading, without rifles or other equipment, and then a single Home Guard member demonstrates loading an SMLE. From the footage we can get an idea of how the weapon would have worked.

Three-man crews sit by their weapons note the troughs projecting from the front of the launchers

The men run to the launchers, which appear to be made of wooden boards. Beneath them are rifle stock shaped pieces which the man at the rear seems to shoulder – probably to aim the weapon. The other two crew members kneel either side of the launcher. The footage then cuts away to another angle from the other side and shows one of the kneeling men hitting the rear of the projectile with a hammer. Then with a flash and puff of smoke the projectile launches forward. The man who aimed the weapon appears to have moved away, out of shot. Frustratingly the footage is a bit underexposed and quite dark so we can see too much more detail but we can see that the chap with the hammer is definitely hitting the rear of what looks like a length cylinder. The cylinder shoots to the rear while a projectile fires forward and the launcher’s crew look downrange.

A somewhat low resolution close-up of the launcher. Note the crew member lying behind it aiming it along the wooden piece on the right. The projectile and launch cylinder sit in a trough while behind appears to be a shield to protect the crew member aiming

We then get footage showing what seem to be a series of impacts, likely from the projectile’s fired by the launchers. Then we get another clip of the men running to man the launchers and some more shots of the incendiary weapons exploding. From the available footage its pretty difficult to theorise how the launchers work. They appear to be using an almost proto-recoilless rifle-like principle with the launch cylinder shooting backwards and the projectile leaving the cylinder and firing towards the target. The crew member with a hammer may be hitting a percussion cap to detonate some black powder which projects the incendiary bomb. This system may have been developed to remove the need for a fixed, pressure bearing barrel. Making the weapon much simpler to manufacture.

The effect down range – the target well alight

The footage doesn’t give us too much indication of the range of the weapon but it’s distant enough that the men firing the weapon don’t appear to recoil when the projectile hits the target. The incendiary effect downrange is actually quite impressive and a battery of five of the launchers would have been an impressive sight and perhaps quite useful as a road ambush weapon which was something the Home Guard focused heavily on at the time.
It wasn’t until later in 1941 that sub-artillery like the Smith Gun, Northover Projector and the Blacker Bombard began to enter service with the Home Guard. Until then some of the units took it upon themselves to create their own weapons, improvising contraptions like the one featured in this video.

Update 28/07/21:

The weapon somewhat fits the description of the ‘Jones-Wise Projector’ shared by David Lister in his book Forgotten Tanks and Guns. Thanks to BettongMI who brought this to my attention in the comment section of the video. The weapon was apparently developed by a pair of Home Guard officers and while turned down for regular service was used by some elements of the Home Guard in southern England, at least until official sub-artillery began to enter service.


If you enjoyed this video and article please consider supporting our work here. We have some great perks available for Patreon Supporters. You can also support us via one-time donations here. Thank you for your support!


Bibliography

Home Guard and home-movies in Swanmore, Wessex Film and Sound Archive via the BFI, (source)

Britain’s Final Defence: Arming the Home Guard, 1940-1944, D. Clarke (2016)

Forgotten Tanks and Guns of the 1920s, 1930s and 1940s, D. Lister (2018)