In this article, Christopher Dwulet, author and editor for Ammo.com looks at the 50-calibre gun in use by the RN from the 50 Vickers and up to the 50 Browning Machine Gun still in use today.
There’s something special about shooting a 50 calibre. The standard 7.62x51mm NATO is an excellent cartridge that has proven itself on the battlefield time and time again. But when you squeeze the trigger on a 50 cal, it’s a completely different experience! Although 50 calibre heavy machine guns have been extensively employed by the Royal Marines and British Army for many years, recently the RN began re-evaluating the effectiveness of the 50 Browning for equipping its surface ships. (‘50 calibre’ refers to the diameter of the bullet which is .50 inches or 12.7 millimeters.)
The 50 Vickers – Britain’s first fifty
The 50 Vickers or 0.5-inch Vickers was developed towards the latter part of World War I to meet the needs of the British Army. At the time a round that was effective against light armoured vehicles, planes, and tanks was needed. An anti-aircraft round was also an urgent requirement as Britain was being raided by the first generation of German bombers. These aircraft were able to absorb an absurd amount of .303 bullets from British interceptors without sustaining critical damage. The 50 Vickers was able to deliver the armour-piercing explosive or incendiary payload needed to down these aircraft quickly and efficiently.
The 0.5 Vickers was developed by Eley Brothers (Eley Limited today) by necking down the 600 Nitro Express to accept a 50-calibre bullet. The initial design utilised a rimmed case and fired a round-nose bullet. Further development of the cartridge case removed the rim and added a belt similar to the 375 H&H Magnum. The belted cases were headstamped ‘ELEY .600/500’, later versions of the case that were reinforced were labelled ‘ELEY .600/500A’. The new round was developed for use in a scaled-up version of the water-cooled Vickers and Lewis machine guns. The initial armour-piercing round fired a 570-grain bullet loaded with 135 grains of Dupont No.16 nitrocellulose resulting in a muzzle velocity of 2,650 feet per second (FPS).
The Royal Navy took note of the 50 Vickers’ anti-aircraft capabilities and adopted the platform in what became known as the Mark III. The Mark III was an anti-aircraft gun that consisted of four Vickers machine guns chambered for the 50 Vickers round. Each machine gun was loaded with a 200-round belt-fed magazine for a total of 800 rounds of 50 Vickers. The quad guns were adjusted to provide a cloud of plane-evaporating lead approximately 60 feet (18 m) wide and 50 feet (15 m) high at 1,000 yds (910 m). With a cyclic rate of 700 rounds per minute, the Mark III could completely unload its magazines in approximately 20 seconds.
Although the Mark III was very effective against biplanes of the WWI era, the Royal Navy quickly understood that the 50 Vickers simply didn’t have enough firepower or speed to take down the new generation of faster and tougher aircraft. To combat this new threat, much of the fleet was outfitted with 20mm Oerlikon cannons or the heavier QF 2-pounder 40mm Autocannons (known more commonly as the ‘pom pom’). By the start of the second world war, the Mark III started to be phased out of naval service, except on coastal forces craft.
WWII brings the 50 BMG to the Royal Navy
In 1921, American gun and cartridge maker John Moses Browning released his version of the 50-calibre cartridge. The 50 Browning Machine Gun (50 BMG) or 50 Browning was developed to fill many of the same roles as the 50 Vickers. (More about the development of the 50 Browning on Ammo.com here.)
Although comparisons between the 50 Vickers and 50 Browning were immediately made, until the second world war, the Admiralty seemed to favour the Vickers round over the 50 BMG. Trials were run in 1928 and 1934 comparing the two rounds, but in both cases, the 50 Vickers was selected over the American round. By comparison, the 50 BMG is the larger of the two rounds as the Browning measures 12.7×99 mm compared to the smaller 12.7×81 mm of the Vickers.
Although the RN was resistant to putting American weapons on British warships, the Blitz changed all that. In May 1941, President Roosevelt enacted the Lend-Lease Act whereby large quantities of military equipment were sold to Britain to hold the Axis powers at bay. It was then that the 50 Browning and its corresponding M2 heavy machine gun entered British military service. Although initial shipments of 50 Browning ammunition were made in the US, British manufacturers began production after 1941. Today Browning is owned by General Dynamics and the 50 Cal is still in production for forces around the world.
The L111A1 50 Cal used by UK forces is an automatic, belt-fed, recoil-operated, air-cooled, crew-served gun equipped with a flash suppressor and a spare barrel assembly. A disintegrating metallic link belt is used to feed the ammunition into the weapon which can be set up to feed from either the left or right side. The gun is capable of being modified to fire in single-shot mode but is predominantly used in automatic, firing 545 rounds per minute with a muzzle velocity of 930 m/s.
The 50 Browning or 12.7×99 mm NATO round has been used in combat since WWII. Its primary focus was as an anti-material cartridge, capable of blasting through brick walls, disabling vehicle engines, and lightly armoured targets. Early rounds were loaded with an 800-grain bullet fired at a muzzle velocity of 2,580 fps (786 m/s). Considerable development was performed on the 50 Browning round, and today numerous types of bullets are available for a multitude of military purposes.
Standard full metal jacket ammo is available for anti-personnel or unarmored targets, while armour piercing (AP) or armour piercing incendiary (API) rounds can be utilised on harder targets. For heavier targets that require a bit more power, military shooters prefer the Raufoss Mk 211 Mod 0 HEIAP (high explosive incendiary armour piercing) rounds for when you really want to get the job done.
Modern 50 Browning ammo is typically fired from a 1:15 twist-rate barrel with eight lands and grooves. It has been proof/test pressure listed at 450,000 kPa and can produce between 14,000 and 20,000 J of muzzle energy depending on the load. Given the heavy bullets fired by the 50 Cal, it is one of the few rifle cartridges that can boast a ballistic coefficient of 1.0. By comparison, the 7.62x51mm NATO has a G1 ballistic coefficient of around 0.40. Ballistic coefficient is a measure of how resistant a bullet is to wind deflection, and with a BC of 1.0 it is excellent for long-range shots beyond 1,000 meters.
The 50 cal in the RN today
Although the 50 Cal L111A1 Heavy Machine Gun has seen extensive use with the Royal Marines and British Army, the RN has generally preferred the lighter M134 Mk 44 Mini gun or L7A2 General Purpose Machine Gun (GPMG) for force protection.
The Fleet Air Arm has used the M3M 50-cal variant made by FN Herstal for some years when they are providing air cover or hunting down smugglers. The M3M can be fitted to Wildcat and Merlin helicopters and is adapted for aircraft use, featuring a firing mechanism that fires from the open bolt, internal recoil spring and a perforated barrel jacket. It has been considerably up-rated to fire up to 1,100 rounds per minute and a soft pintle mount and dual recoil buffer system reduces vibration transmitted to the airframe. Rounds are fed into the gun via a feeding chute that connects to a 600-round ammo box and spent cartridges are collected via another chute.
Despite its much greater hitting power than the GPMG or Mk 44, The 50 Cal benefits from being very reliable and robust, sufficiently light enough to be manhandled around the upper deck and easily mounted for use or removed for securing or for maintenance as needed. It can also be fitted with a variety of sights either simple iron sights, ring sights night vision or other optical sights above the spade triggers.
The 50 cal has now completely replaced the Mk44 mini gun which officially went out of RN service in March 2023, this is thanks to its longer effective range when compared to the 7.62x51mm rounds. This is driven in part by ever-evolving threats such as piracy and terrorist groups that favour smaller craft such as speed boats, jet skis, and RIBs for hit-and-run operations, The 50 Cal makes more sense as it allows sailors to engage potential threats at greater distances and can rip these craft apart at 2,000 meters even with simple ball ammunition.
When fixed to a standard pintle mount on a moving warship, the accuracy of the weapon is limited, especially beyond 1,000m. In November 2021 the NavyX and DSTL conducted a trial of a new Agile, Small-deflection, Precision (ASP) mounting on board HMS Argyll. The ASP mount is made in the US by Flex Force and uses gyroscopic stabilisation, increasing the accuracy and concentration of fire, especially in heavy seas. The trials team fired 5,000 rounds at static targets and a moving radio-controlled target boat. 3,500 rounds were fired using the new mounting for comparison with the old mount. At the time of writing it is unclear if the RN will invest in this upgrade for use across the fleet.
a very good reliable piece of kit that has stood the test of time,and i think it will still be around for a very long time..
For close range use against soft small targets maybe but not much use as anti-air, anti-surface, and anti-sub defense.
Yeah and a stingray torpedo can’t do much against a air attack. So what’s your point?
Yep and that is a big threat for modern escorts, asymmetric warfare is very much come of age…even large militaries are now using all sorts of drones etc.
Experiences in Ukraine have shown that it is hard to shoot down drones, especially in the dark with a 50 cal, for drones, a ship is a much bigger target,
I was talking about surface drones.
Not sure of it’s military effectiveness but it should definitely be kept in widespread service for morale purposes. Everyone is happier after cracking off a few rounds with a. 50 cal in training
Not sure of it’s military effectiveness
You stand in front of it while we all take turns then. 🙂 😉
Hopefully the APS mount works as advertised. If not I think the RN will need to look at finding funding to upgrade at least some of the gun positions to use one of the RWS on the market. Theses systems significantly increase the hit percentage at longer ranges.
No need for RWS. The ships already have RWS in the form of the DS30M mounts which are obviously far more effective. Where manual mounts win out is response time, particularly in harbour/at anchor or in close. Thats the real utility of the .50, GPMG or Minigun.
Wont the 30mm have too much range in some restricted anchorages and even open ocean there could be other allies ships with 5km which puts them within the fire zone for a 30mm that could miss its target
It is the smallest calibre that allows all sort of exciting natures worthwhile.
Any chance of that in the King’s English
Um. Yes. I don’t know why I said worthwhile. I should have said ‘possible’.
The only mitigation I can offer the court was that it was very busy around here these morning with tradesmen plus obviously it is Friday.
Does that help?
Different natures of .50 BMG…………..
I remember what I was saying now. .50 is about the right size to make things like AP work well. Yes there is 7.62 AP say, but the extra oomph and mass make .50 AP ‘better’.
It’s certainly stood the test of time. When you think what could replace it you realise just how good at it’s job it is. I can only think of a Mk19 AGL that could replace it. At least shipborne.
One advantage the minigun has over the 50 cal. Is the ability to walk effective fire onto the target. This is done by firing burst, watching the tracer and adjusting lead to hit the target. Its very effective. When firing the 50 cal does wander around the aim point, especially if it doesn’t have the shoulder brace fitted.
I am surprised the Navy didn’t explore looking at the GAU-19. This is a 50 cal three barrelled electrically driven minigun. With a selectable rate of fire between 1000 and 2000rpm. The thing is a beast, guess the Navy didn’t want its WEs having too much fun!
Is it maranised?
Salt water is not kind to weapons systems!!
Gunnery is Funnery.
Except as the maintainer when you have to sort out the mess the operators leave behind!
“Gunnery is Funnery”
‘three barreled electrically driven’ There’s the key.
That platform while fearsome when getting a steady diet of ammo and juice, if the ship takes any damage and you loose power, you’re just left with deck decoration.
7.62 Minigun is electrical. It has a huffing big rechargable battery on the deck next to the ammo bin. Same can be arranged for any mini gun. Even the 30mm mount is battery powered if you lose ships mains.
Lesser known fact. With the M134 and I suspect the GAU-19, even with no electrical power, if you turn the barrel and the gun is loaded, it will fire. The firing pins are mechanically cam operated.
I was on a RFA last week and it still has MiniGuns… Pretty sure the other RN ships I see most days have them as well.
It’s going out of service for some reason I cannot fathom.
Interesting stuff about the Vickers 50 calibre and the drivers that pushed its development in WW1 — heavy bullet to bring done wood and string aircraft.
Just wish the RAF / Treasury had read the reports during the interwar years.
WW2 — RAF with .303 onboard — Battle of Britain lasts 3 months.
RAF with 50 calibre onboard or 20mm cannon — Battle of Britain lasts only 3 weeks.
Conjecture of course but it should never have been such a close run thing.
From memory — talk at the time had the Luftwaffe squadrons running competitions for the crew that made it back with the most bullet holes.
You had to be in the low hundreds to make the top 3.
Today — leave the 50 calibre for Somali technicals.
Looks a bit cheap / low rent for tip of the spear naval uses.
We need more hulls in the water rather smaller and smaller guns to deal with low cost DIY threats.
The .303 browning used in the early Spitfire/Hurricane wasnt a single gun , it was 4 guns in each wing designed to concentrate volume of fire at the same predetermined distance or aim point.
At the time the target was an enemy bomber and they assumed only 1 or 2 sec so it was higher rate of fire of .303 against 50 cal. Testing showed the 50 cal didnt do much more damage
Having real world air to air battles showed that going to fewer explosive 20mm cannon shells was better not because Treasury had stiffed them- your schtick you make all the time, (are you sure it wasnt freemasons or worse)-
US fighters preferred 50 cal over .303 for the same reasons but with their much much bigger fighters than the diminutive Spitfire/Hurricane
Nugget on show — MOD analysis vs real world results.
Some people learn from their mistakes — the MOD just keep repeating them every 25 years.
4 gun mania took over the MOD / UK defence thinking during the 30’s with the usual disastrous results.
With the RAF it was the perceived need to put a specific number of bullets into planes / targets that were improving rapidly regarding speed / performance with the move towards 1000hp engines and better monoplane aerodynamics.
Then you have the old wives tale regarding the calcs that pushed the 8 gun warload on the 1933/35 fighter designs — great story but lacking in the depth of analysis needed for a useful armament.
The faster targets came with a much more robust structure needed to cope with the greater speeds / higher aerodynamic loads so .303 was old thinking.
Plus the move towards greater defensive sophistication — armour / self sealing tanks — made the situation even worse. Cue real world failure with the .303 armed units that needed some crash course engineering to get 20mm cannons onto 1930’s era fighter designs that we took into WW2.
The RN had similar issues — 4 gun turret on the KGV class was an engineering marvel but real world disappointment in a world of idiotic / idealistic rule following that was very close to self hatred.
I think you will find that the Treasury was involved.
Phew — the Belfast class cruisers had a lucky escape.
Although the same flawed thinking was involved.
Lots of old school light shells instead of the latest thinking / something bigger.
Super heavy was the way to go but it was not for the likes of us.
It seems that you have never heard of the actual constraint in that era , the various naval Treaties. The rest of your claims have no substance nor backed by research
Naval treaties …
The Treasury loved Washington.
The US read our diplomatic cables and made their proposals Treasury friendly to generate acceptance.
The Treasury wrote the London proposals to save money — battleship limit of 25K tones / 12″ main guns — they ran it up a flagpole and no-one saluted.
Common knowledge that people were cheating on the Washington Treaty limits — Japan started it with heavy cruisers and Germany followed with “pocket battleships” then Italy and Germany followed suit with their battle ship designs.
The RN was held back by politics and economics.
Escalator clause came in allowing 45K ton units — the Treasury would only sign off 40K tons for the Lion Class although they missed the last 550 tons to the rounding allegedly.
So 30’s MOD / RN thinking was poor and the Treasury made things worse
The Treasury thought that the 1940 RAF was in a good place — all monoplanes in.production — lasted 30 minutes in combat to see the challenges ahead.
I fear we are in a similar place today.
Germany wasnt signatory to either 1922 Washington nor 1930 London Naval treatys, so pocket battleships were not designed under those restrictions
1922 Treaty provision for UK wasnt *saving money* as they were the only one allowed to build new battleships
Brown, David K.. Nelson to Vanguard: Warship Design and Development, 1923–1945 (p. 569). Pen & Sword Books. Kindle Edition.
Im sure the UK made the most of home ground advantage in decoding signals in 1930 London treaty.
Admiral Chatfield said the treatys biggest effect was discourage innovation and lock in Britains post WW1 status quo.
The 1935 UK-Germany naval treaty was cunning in that it allowed more battleships and cruisers – which would be easiest for Britain to defeat ( as happened) and diverted money from an even larger pre WW2 U boat fleet which was the real threat
Cherry-picking the points you want to answer.
Very ironic given the subject matter involved — Cherry Tree Class anyone …
Properly armed RAF in 1940 — 20mm cannons — then the Battle of Britain would have lasted 3 weeks and not the three months that it did.
Highlights flawed MOD analysis — something we need to re-learn for today and that would include the RN’s AAW capabilities.
Providing the Luftwaffe with an inexhaustible supply of targets for 3 years was not the start to WW2 that we needed.
No matter the treaty involved — Versailles vs Washington vs London — the “panzer kruiser” design was well over its allotted displacement and the MOD / RN knew it and did nothing.
They stuck rigidly to rules of their own making and we paid a heavy price for their rank stupidity — the whole episode flagged up the societal pressures towards a re-run of the Great War in Germany and we did nothing.
Revoking the 10 year rule would have been a start even if it was even by then already too late.
Washington — the Treasury was playing the long game.
It wanted a 15 ship battlefleet not an 18 ship / 20 ship / 22 ship one that was needed for “Empire” defence and that is what it got.
The resulting Nelson Class were a cheap parts bin special that makes even the current QE class look good — low effort re-heats of the 1920 battlecruiser design with their failed light shells and their narrow main belt.
Too slow from the off — two knots slower than the existing Mutsu class — and destined to be tail end Charlie’s for their entire career.
Much better if they had given up X turret and doubled the installed power for a much more usable ship with the added benefit that they might have been able to build more of them to equal the USN’s total of 24 x 16″ guns afloat.
An extra couple plus HMS Tiger and things would have turned out differently when the bullets started to fly. But that was not what the Treasury wanted.
London Treaty — you are having a giraffe.
Nobody took a blind bit of notice of it apart from us and our 14″ guns — the 1930’s MOD obsession with the “power of 4” writ large,
Plus the code breaking fantasy — not good.
Anglo German Naval Treaty — some sort of MOD swizz?
Sick joke more like.
Ask the Glorious?
Ask the Hood?
RN — 12 attempts to sink the Tirpitz — all failed.
Huge pantomime in the Arctic Ocean trying to fight battles we had already lost — thank heavens for Iran.
If that counts as a success then you must have a stiff upper lip made out of cast iron.
You’re missing out the st Petersburg declaration. In which it was against international law to use with explosive rounds of less that 400g this actually made it against international law to use 20mm cannons…the UK government knew others were exploring cannons against treat but decided not to break the treaty themselves so they were late to the cannon game.
the raf did actually have a number of cannon armed aircraft in 1940 including the spitfire Mrk1b armed with 2 20mm cannon and they did not perform very well at all..infact they were pigs and 19 squadron requested they have there browning armed Mrk1s back,
Also the BF109 of 1940 has no armour at all and was completely vulnerable to the 8 Brownings 303.
another key point was that the reason 8 Brownings were used was accuracy of gunnery…simply put your average pilot struggled to hit another fighter in a dog fight and if they were in a cannon armed aircraft it reduced their accuracy even more. So cannons and lower rate of fire weapons with high impact only really helped those pilots with very very good gunnery skills or against slow easy targets.
where the 303 struggled vs a good cannon armament was against larger multi engined bombers that on average needed thousands of rounds…
So to say say the 8 gunned spitfire and hurricane lenghed the battle of britian is not right…if they had armed every spitfire with the 2 20mm. Cannons of the Mk1b Britain would have lost the Battle of Britain as they were shite.
Considering this fantastic firearm has been used to shoot down aircraft from the ground and in the sky…it will remain a firm favourite of mine. If it isn’t broken….don’t fix it 😀
Perhaps would be wise to have both the 50 cal and the Mini gun in addition to the GPMG !! Mini gun as a back up on case the 50 cal doesn’t quite do the job !
Simple question, to what extent are we going to have to expand the close in armament of Naval vessels?
There is absolutely no reason that in not more than half a decade we will be facing various types of autonomous drones with ability to recognize particular classes of vessels and attack particular parts of those vessels.
I hear the Spanish are fitting pods to the Juan Carlos.
Nothing wrong with the weapon -if it ain’t broke etc…..
Has any thought been given to upgrade the ammo this gun fires? Like rocket propulsion ?
The GyroJet pistol had a similar system. With better manufacturing it could give the 50cal more bite.