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.


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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)

My New Book on the PIAT is Out Now!

I’m very excited to say that my second book has been published! It looks at the much maligned and much misunderstood PIAT – Projector, Infantry, Anti-Tank.

The book is available from retailers from the 20th August in the UK/Europe and the 22nd September in the US – but you can order a copy from me now regardless of location. I filmed a short video to show you the book and talk a bit about the process of writing it, check that out above.

The PIAT was the British infantry’s primary anti-tank weapon of the second half of the Second World War. Unlike the better known US Bazooka the PIAT wasn’t a rocket launcher – it was a spigot mortar. Throwing a 2.5lb bomb, containing a shaped charge capable of penetrating up to 4 inches of armour. Thrown from the spigot by a propellant charge in the base of the bomb, it used a powerful spring to soak up the weapon’s heavy recoil and power its action.

With a limited range the PIAT’s users had to be incredibly brave. This becomes immediately obvious when we see just how many Victoria Crosses, Military Medals and Distinguished Conduct Medals were awarded to men who used the PIAT in action. 

The book includes numerous accounts of how the PIAT was used and how explores just how effective it was. I have spent the past 18 months researching and writing the book and it is great to finally see a copy in person and know it’s now available.

The book includes brand new information dug up from in-depth archival research, never before seen photographs of the PIAT in development and in-service history and it also includes some gorgeous illustrations by Adam Hook and an informative cutaway graphic by Alan Gilliland.

If you order a book directly from me I’ll also include this custom illustrated postcard with a design featuring a PIAT and the famous line from A Bridge Too Far.

It’s immensely exciting to know the book is out in the world for all too enjoy. If you’d like a copy of my new book looking at the PIAT’s design, development and operational history you can order one directly from me here!

Me, bringing up the PIAT…

Thanks for your support and if you pick up a copy of the book I really hope you enjoy it! 

– Matt