The well known heavy Browning was a prime weapon on US-produced combat aircraft of ww2. How good/bad would it be for other air forces, if adopted just pre-war? How about further developments of the system, like the Japanese Ho-5 20 mm cannon, or just necking out the cartridge so HE shell might be introduced (not unlike what Soviets did with their slightly bigger 12.7mm)?
0.50 Browning MG and it's descendnats for 'other' air forces?
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
buffnut453
Captain
What date are you selecting as the start of the war?
- Thread starter
- #3
Shortround6
Major General
Ok, we have gone over some of this before. The Browning .50, like some other things, was evolving/changing during the war. Cycle rate rated changed from 600rpm (or under) for free firing guns to 800-850rpm in 1940. Apparently not a big/difficult change. But which air force gets which guns pre-war? the slow firing or the fast firing? The gun it self seems to have been fairly reliable but many installations were not. It might have had trouble with belt pull (how much weight of ammunition belt it could pull or lift.) Some American turrets got electric motors to help move the belts and these motors were later used in field modifications in P-51Bs and Cs. P-51Ds didn't use them (?) and P-40s/P-47 and Navy planes didn't. but moving belts in wings with ammo the same height as the gun is not the same as trying to lift the belt from storage boxes beneath and seated mans feet in a top turret.
Necking out the cartridge takes a lot of planning and investment for not a lot of return. The American cartridge was 20.3mm across the base in front of the rim vs 21.8mm for the Russian round. Chances of using a 20mm projectile from the American case is about zero. It means you have design all new 17-19mm projectiles and fuses and not using adapted parts/projectiles even in testing. It also puts you up against the the cube law for projectiles. Given a similar shape changing the caliber of the projectile will change it's weight by the cube of the diameter. as a rough guesstimate an 18mm projectile will weigh about 73% as much as a 20mm projectile. Of course 20mm projectiles ranged from 79 grams to 134 (or more?) so you have to pick and choose carefully. The German 15mm HEI projectile weighed 57 grams.
For some air forces you have to balance out the weight of the gun and ammo ( one .50 round weighed about 5 times what rifle caliber ammo did) against what engines they had available. A lot of the early American aircraft with 1000-1200 engines suffered from being saddled with too much weight of guns and ammo.
The Gun was made by FN in Belgium Pre-war and they may have gotten a higher rate of fire out of it. Considering the trouble the Americans had getting it to 1200rpm any claims of prewar FN guns firing that fast in service must be viewed with suspicion.
Scaled down to take the British/Italian/Japanese 12.7mm round it might have done fairly well for some nations. Scaled up it might also have done OK. Japanese had quality control problems and material shortages and the Browning didn't tolerate either one very well.
The original 1917 had to be modified to the 1917A1 when it turned out the receiver wasn't quite strong enough (perhaps due to substandard material or heat treatment ?)
The "saddle" or reinforcing on the lower receiver was not present on the original 1917 guns.
we start getting into 'what ifs' regarding materials and hypothetical rates of fire.
Necking out the cartridge takes a lot of planning and investment for not a lot of return. The American cartridge was 20.3mm across the base in front of the rim vs 21.8mm for the Russian round. Chances of using a 20mm projectile from the American case is about zero. It means you have design all new 17-19mm projectiles and fuses and not using adapted parts/projectiles even in testing. It also puts you up against the the cube law for projectiles. Given a similar shape changing the caliber of the projectile will change it's weight by the cube of the diameter. as a rough guesstimate an 18mm projectile will weigh about 73% as much as a 20mm projectile. Of course 20mm projectiles ranged from 79 grams to 134 (or more?) so you have to pick and choose carefully. The German 15mm HEI projectile weighed 57 grams.
For some air forces you have to balance out the weight of the gun and ammo ( one .50 round weighed about 5 times what rifle caliber ammo did) against what engines they had available. A lot of the early American aircraft with 1000-1200 engines suffered from being saddled with too much weight of guns and ammo.
The Gun was made by FN in Belgium Pre-war and they may have gotten a higher rate of fire out of it. Considering the trouble the Americans had getting it to 1200rpm any claims of prewar FN guns firing that fast in service must be viewed with suspicion.
Scaled down to take the British/Italian/Japanese 12.7mm round it might have done fairly well for some nations. Scaled up it might also have done OK. Japanese had quality control problems and material shortages and the Browning didn't tolerate either one very well.
The original 1917 had to be modified to the 1917A1 when it turned out the receiver wasn't quite strong enough (perhaps due to substandard material or heat treatment ?)
The "saddle" or reinforcing on the lower receiver was not present on the original 1917 guns.
we start getting into 'what ifs' regarding materials and hypothetical rates of fire.
- Thread starter
- #5
I've picked the BMG not to start another 'cannon vs. HMG debate', but rather some of it's points that made it suitable for aircraft armament. Eg. it was one of the (or the)most powerful belt-fed guns until Shvak came along, yet light enough so multiple guns could be carried even with fighters with 1000-1200 HP onboard.
A cannon of 18mm should give us, say, an 80 g HE shell, 70 g Mine shell, with MV of 700-750 m/s? The RoF would've probably start at around 600 rpm, increase of up to 850 rpm was for the Japanese Ho-5 cannon, though Wikipedia gives 950?
The P-39 might've benefited with 3 'cannoncinos' only; synchronization kills Rof down to 500, so it would be 800 + 1000 rpm for the trio. Maybe adding another one synchronized, between the two? Wing guns ammo deleted, of course. The P-38 with 5, P-47 with 6, remainder of S-E fighters with 4?
In case British decide to make the 18mm, 4 for Hurri and Spit? Or 2 of those, plus 4 MGs in time of BoB?
Germans - 2 for Bf 109E (HMG for the earlier versions), the 3rd added in central position? 4-6 for the Fw 190?
Re. Ho-5: looks like the gun was okay from get-go:
A cannon of 18mm should give us, say, an 80 g HE shell, 70 g Mine shell, with MV of 700-750 m/s? The RoF would've probably start at around 600 rpm, increase of up to 850 rpm was for the Japanese Ho-5 cannon, though Wikipedia gives 950?
The P-39 might've benefited with 3 'cannoncinos' only; synchronization kills Rof down to 500, so it would be 800 + 1000 rpm for the trio. Maybe adding another one synchronized, between the two? Wing guns ammo deleted, of course. The P-38 with 5, P-47 with 6, remainder of S-E fighters with 4?
In case British decide to make the 18mm, 4 for Hurri and Spit? Or 2 of those, plus 4 MGs in time of BoB?
Germans - 2 for Bf 109E (HMG for the earlier versions), the 3rd added in central position? 4-6 for the Fw 190?
Re. Ho-5: looks like the gun was okay from get-go:
From here.
Last edited:
Shortround6
Major General
It kind of depends on when and what weight (and money) you are willing to devote to armament.
A MK II Spit carried about 430lbs. 254lbs for the eight .303 Brownings. 31.75lbs per gun. that is from a Spitfire Weight and load chart. 2800 rounds (350rpg)weigh 186lbs or 6.64lbs per hundred.
An F4F-3 Wildcat had four .50 cal guns that weighed 286lbs. .50 cal ammo weighed about 30lbs per hundred depending on bullet mix and links. Normal load was given as 360lbs or about 300rpg. Overload was 516lbs of ammo or 1720 rounds (430rpg).
If you want to keep the Sptifire's weapon load you have about 130rpg for four .50 cal guns.
A Spitfire with 2 belt feed cannon and four MGs had an armament weight of 650lbs (MK Vc and later) or just about what the Wildcat with four guns and 300rpg had.
These weights do not include ammo boxes/trays. some mounts/local reinforce, gun controls and gun heating arrangements.
For the early 109s the Browning weighs within a KG of what the MG FF did. Replacing it one for one seems easy enough, question is the ammo. It appears (open to correction) that 60rounds plus drum went about 20kg for the MG FF or 44lbs, rounding up gives us about 150rpg for the Germans to use in the wings of the 109 if they keep the weight about the same. Do the Germans get the 600rpg guns or the 800rpm guns? Granted the 109E-3s can loose about 500 rounds per gun from the cowl guns and not hurt much of anything but that only saves about 60lbs. Enough for another 100 rounds for each wing gun.
The Americans and Soviets never came up with exploding ammo (or even high capacity incendiary ammo) for their high velocity 12.7mm guns. I am not sure why. Germans, Italians and Japanese did for their lower velocity 12.7-13mm guns. Japanese had trouble with prematures. It could be they didn't want to bother with fuses that small. It could be that the higher velocity and higher pressures acting on the base of the projectiles required stronger construction, cutting down on an already low HE content. I don't know.
According to the chart on Tony Williams web site the the six gun P-40 had just 12 KG less armament than a Hawker Typhoon with four 20mm cannon and 22kg more weight than a Fw 190A-4 with two 7.9mm, two 20mm MG 151s and two 20mm MG FF/ms and about 100kg less than a FW 190A-8 with two 13mm guns and four 20mm MG 151s. I would note that there are a few mistakes in the chart so until somebody adds the weights up to double check we may want to take it with a grain of salt.
The .50 was cursed not only with it's own weight but it's heavy ammo. A single round goes about 112grams compared to the 162 grams to over 250grams for 20mm ammo. Unfortunately the only common 20mm round that weighs twice waht a .50 cal round does (or a bit more) is the Hispano. The German, Italian and Japanese 12.7-13mm rounds were about 70-75% of the weight and some of the lighter 20mm cannon rounds were only about 65% heavier.
The American .50 also does not play well with others
While it is a pretty good ballistic match for the 20mm Hispano it it more of a mismatch for most other countries guns. It's high velocity and streamline bullet means it's time of flight is going to be rather different than most other peoples 20mm guns and RCMGs.
A MK II Spit carried about 430lbs. 254lbs for the eight .303 Brownings. 31.75lbs per gun. that is from a Spitfire Weight and load chart. 2800 rounds (350rpg)weigh 186lbs or 6.64lbs per hundred.
An F4F-3 Wildcat had four .50 cal guns that weighed 286lbs. .50 cal ammo weighed about 30lbs per hundred depending on bullet mix and links. Normal load was given as 360lbs or about 300rpg. Overload was 516lbs of ammo or 1720 rounds (430rpg).
If you want to keep the Sptifire's weapon load you have about 130rpg for four .50 cal guns.
A Spitfire with 2 belt feed cannon and four MGs had an armament weight of 650lbs (MK Vc and later) or just about what the Wildcat with four guns and 300rpg had.
These weights do not include ammo boxes/trays. some mounts/local reinforce, gun controls and gun heating arrangements.
For the early 109s the Browning weighs within a KG of what the MG FF did. Replacing it one for one seems easy enough, question is the ammo. It appears (open to correction) that 60rounds plus drum went about 20kg for the MG FF or 44lbs, rounding up gives us about 150rpg for the Germans to use in the wings of the 109 if they keep the weight about the same. Do the Germans get the 600rpg guns or the 800rpm guns? Granted the 109E-3s can loose about 500 rounds per gun from the cowl guns and not hurt much of anything but that only saves about 60lbs. Enough for another 100 rounds for each wing gun.
The Americans and Soviets never came up with exploding ammo (or even high capacity incendiary ammo) for their high velocity 12.7mm guns. I am not sure why. Germans, Italians and Japanese did for their lower velocity 12.7-13mm guns. Japanese had trouble with prematures. It could be they didn't want to bother with fuses that small. It could be that the higher velocity and higher pressures acting on the base of the projectiles required stronger construction, cutting down on an already low HE content. I don't know.
According to the chart on Tony Williams web site the the six gun P-40 had just 12 KG less armament than a Hawker Typhoon with four 20mm cannon and 22kg more weight than a Fw 190A-4 with two 7.9mm, two 20mm MG 151s and two 20mm MG FF/ms and about 100kg less than a FW 190A-8 with two 13mm guns and four 20mm MG 151s. I would note that there are a few mistakes in the chart so until somebody adds the weights up to double check we may want to take it with a grain of salt.
The .50 was cursed not only with it's own weight but it's heavy ammo. A single round goes about 112grams compared to the 162 grams to over 250grams for 20mm ammo. Unfortunately the only common 20mm round that weighs twice waht a .50 cal round does (or a bit more) is the Hispano. The German, Italian and Japanese 12.7-13mm rounds were about 70-75% of the weight and some of the lighter 20mm cannon rounds were only about 65% heavier.
The American .50 also does not play well with others
While it is a pretty good ballistic match for the 20mm Hispano it it more of a mismatch for most other countries guns. It's high velocity and streamline bullet means it's time of flight is going to be rather different than most other peoples 20mm guns and RCMGs.
I imagine they came to the conclusion that the effectiveness of an explosive .50-calibre round wasn't worth it. Using the British 'de Wilde' incendiary was a much better choice in my opinion.
Not sure what the Russians used.
kool kitty89
Senior Master Sergeant
The lighter Japanese Army adaptation is indeed interesting, though so is the heavier 13.2 mm Japanese Navy one, and more so the sheer breadth of developments into cannons the Japanese Army managed. It shows a potential for the basic design that everyone else (even its original designers) apparently missed. (though at one time on the forums here there was mention of a .60 cal US adaptation of the browning -not the T17 MG 151 copy- but I never got more definite details on this, though the mention seemed to imply it was a direct adaptation of the existing gun and ammunition case necked out to .60 cal and presumably firing at a somewhat lower velocity)
Regardless of that, the american .60 cal anti-tank rifle round used on the T17 would have made sense as the basis for a heavier gun or 20 mm ammunition as well. (particularly had the Hispano not been adopted) The 23 mm madsen ammunition the US was interested in pre-war would have been very interesting to see adapted to a browning derivative as well. (as would the 37 mm ammo of the Browning M4 cannon, given what the Japanese managed with a 37 mm BMG adaptation, the 23 mm probably would have been more useful though, including on the likes of the P-38 and P-39)
British investing in adapting the browning to larger caliber would have made sense too, perhaps with one or more of the drum-fed oerlikon guns kept as alternatives. (the FFF and FFL were both attractive for wing mounting on fighters ... granted, the British historically only tested the heavier FFS which manifested similar problems to the Hispano)
British and Americans had limited interest in synchronized guns, and the Browning (at least beyond .30 cal) was far from the best performing in this regard anyway, but it at least /could/ be synchronized, unlike the Oerlikon guns or Hispano. (the latter technically could have been modified to do so, unlike the oerlikon, at least if electrical priming had been adopted)
From most of what I've seen on the topic, the Japanese Browning adaptations would have indeed progressed more smoothly (and been more reliable) if not for their material and quality control shortcomings. (ie if similar developments had taken place in the US or UK, for example)
A 15-20 mm 'light' machine-cannon derivative able to be mounted in most cases the existing .50 BMG could would be very useful (something moderately heavier than the existing .50 cal, say close to the MG 151).
Aside from that the above comments on 37 and (especially) 23 mm ammunition would be relevant, possibly practical for wing mounting a well in the 23 mm case, but certainly for nose mounting in the P-38 and P-39.
With anything below 15 mm, the consensus generally seemed to be that HE rounds were ineffective given the limited capacity and space occupied by fuzing. (with mine shells, the 13 mm german ammunition might have been an exception, particularly with HE/I loadings broadening effectiveness) There's the possibility of using unfuzed rounds filled with sensitive high explosive intended to detonate on contact (I believe some .30 cal ammo used PETN filler for this reason), but incendiary fillings seemed to be considered more effective there too. (particularly incendiary fillings that also had low-explosive impact properties -various flash-powder like aluminum/magnesium + oxidizer compositions that acted as contact/impact explosives and incendaries, though I believe De Wilde used nitrocelulose to similar effect)
kool kitty89
Senior Master Sergeant
OK, that's what I'd thought ... barium nitrate flash powder composition that ignites/explodes on impact. What threw me was wiki's article detailing the Mk.VI incendiary as using nitrocellulose Incendiary ammunition - Wikipedia, the free encyclopedia it seems trying to refresh my memory on the subject misinformed me as that article only lists the failed Mk.VI and not the Mk.V or Mk.VII using Dixon's barium nitrate design. (the Mk.VII is the one I particularly remember as it's rather well illustrated in the Incendiary B Mark I.z .5" vickers round)
Untitled Document
I'd imagine that high capacity .50 cal Vickers round would have been popular on aircraft had the british adopted something akin to the Ho 103.
The Mk.VI round wasn't failed at all. That was the initial 'de Wilde' incendiary that made it just in time for the Battle of Britain and was highly sought after by pilots.
The Mk.V is probably what you are referring to. I can't recall details on it - in any case the design either wasn't adopted or saw very, very little service.
The VI was Dixon's "de Wilde" design.
The British gave Dixon's design to the USA, who improved and simplified the design, and this in turn was copied by the British to create the Mk.VII.
All British ammunition used in aircraft used nitrocellulose propellant, and this is probably where the wiki contributor became confused.
The Mk.V is probably what you are referring to. I can't recall details on it - in any case the design either wasn't adopted or saw very, very little service.
The VI was Dixon's "de Wilde" design.
The British gave Dixon's design to the USA, who improved and simplified the design, and this in turn was copied by the British to create the Mk.VII.
All British ammunition used in aircraft used nitrocellulose propellant, and this is probably where the wiki contributor became confused.
Last edited:
- Thread starter
- #12
kool kitty89
Senior Master Sergeant
Correct, the Mk.V was a fuzed explosive/incendiary round deemed too complex and costly to mass produce.
https://sites.google.com/site/britmilammo/-303-inch/-303-inch-incendiary
All military guns/cannon in the modern world were using smokeless powder by that time, the British mostly using Cordite, a double-base propellant with a high fraction of nitroglycerin combined with nitrocellulose and a small portion of petroleum jelly. Alternate loadings seem to have included granulated single-base nitrocellulose powders, presumably with some sort of stabilizing agent.
I could see it being the source of confusion, but it's still a pretty major oversight. (though the actual composition used in Mk.VI and VII rounds seems to be a bit uncommonly cited as well) Though I suppose it could have been further confused by notes regarding transition from cordite to single base nitrocellulose propellants.
Ironically, the Barium Nitrate article on wiki gets it right: Barium nitrate - Wikipedia, the free encyclopedia
- Thread starter
- #14
Part of the answer for the above question is that US went to either combine MGs with a cannon, or went to 6-gun batteries (or more); works well with plenty of installed HP, bad with 1000-1200 HP on-board. Soviets were more interested in cannons, 20/23/37 mm, even 45 mm. The low 'bang-for-buck' of exploding .50 ammo is surely an issue, eg. the Germans didn't bothered much even with MG 151 and went fast to the 20 mm variant.
It was surely a heavy powerful round. Hence my proposal for necking it out. Yes, the weight would go up to around 150 grams, but a fighter that carried, say, 6 x 350 rds, will now be carrying 4 x 350 (or 400) rds, along with 2 guns less; we even cut the drag a tiny bit.
Compared with Hispano II (50 kg), the weight of two '18mm' should be ~60 kg. Where 150 rds of Hispano ammo are carried, 250 rds of the 18mm might go instead (weight-wise). The MV should be lower for the proposed gun, but RoF should go to 3200 rpm for 4 of them, vs. 1200-1300 for the Hisso II. Hispano would fire a more powerful shell, 130 g vs. ~80 g.
For the Germans, the proposed gun would've been fitted more easily in the wings of the Bf 109 than a 'full power' 20 mm cannon, and contrary to the MG FF it would be belt fed. That would also allow to get rid of the cowl LMGs/HMGs.
Since the gun muzzle would be either not protruding, or just a little bit protruding, that would cut a drag a bit vs. a muzzle sticking out a foot or like.
The American .50 also does not play well with others
While it is a pretty good ballistic match for the 20mm Hispano it it more of a mismatch for most other countries guns. It's high velocity and streamline bullet means it's time of flight is going to be rather different than most other peoples 20mm guns and RCMGs.
Going with a bigger heavier projectile would mean lower MV. Eg. the Soviet 20 mm lost ~10% vs. their 12.7mm, the predecessor. For the '18 mm', it would mean going from 880 m/s down to 800 ms.
A light cannon with light enough ammo will mean a homogenous battery, ie. no pressing need to have 'back-up' machine guns. But, need be, it would come along good enough with MG 131 or MG 17 (~750 m/s).
kool kitty89
Senior Master Sergeant
I think it was also partially due to the MG 151 being simple to adapt to 20 mm and the 15 mm cartridge was powerful enough to allow for a reasonably high velocity for a 20 mm projectile as well. (and the 20 mm mine shell was already in production AND more effective than a 15 mm variant would be)
They did later adopt 13 mm HE or HE/I loadings, and those seemed to be more effective than the Italian attempts at 12.7 mm HE rounds. (perhaps due to the slightly larger caliber and experience with thin-walled HE shells?)
With the dimensions of the .50 BMG cartridge, an 18 mm projectile might manage similar or maybe higher velocity than a MG-FF or Oerlikon FF round, but likely less than the FFL, perhaps also similar to the under-loaded cartridges used on the Ho-5. (so likely in the low 700 m/s range for a 100 g projectile)
Using the existing cartridge case dimensions and similar propellant loadings to what the existing .50 cal browning already tolerated would have simplified conversion, but at very least you'd gain weight due to the larger barrel. (same case for the IJN's 13 mm Type 3 using the 13.2 mm Hotchkiss round)
Adopting the 13.2 mm Hotchkiss ammunition itself might have been more attractive for many given its existing production and supply while still having somewhat higher capacity for chemical filler) Any larger calibers would mean new/unique ammunition being produced, but with the .50 BMG parent case there'd certainly be room for some attractive possibilities in the 15-18 mm range as well.
And also bear in mind that you'll be using a weapon that's significantly heavier and with heavier recoil than the Oerlikon FF -due both to the ammunition and recoil smoothing of the API blowback mechanism. (but the belt feed and potential -albeit slow- synchronization abilities would be advantageous) In fact, they'd be heavier than the FFL as well, perhaps not in recoil and likely faster firing, but heavier weapons at least.
The larger, heavier barrels with the slower muzzle velocity and lower rate of fire would probably mean considerably longer barrel life than the existing .50 M2 browning, however.
A .70 caliber round would be just shy of the 18 mm figure (17.78 mm), but for compromise between overall ballistics and projectile size, something in the .60 cal range (15.24 mm) seems like it'd make a lot of sense. In the case of the British, aside from the idea of using a lightened browning chambered for the .5 vickers round, developing a new .60 cal heavy round based on the .50 BMG would have been interesting given it should have fairly similar ballistic performance to the .303 as well as the .50 vickers round. (using a mix of all 3 types of ammunition for varying applications may have made sense as well and avoid the mismatch the .303 and Hispano suffered along with the difficulties in coping with the high weight, and powerful recoil of the Hispano -along with the drum feed of the early Hispano marks and Oerlikon guns)
Shortround6
Major General
Ok, just so we are somewhat on the same page.
From Tony Williams website. CANNON, MACHINE GUNS AND AMMUNITION
Please note that if you keep the same receiver length (a quick conversion) you are pretty much limited to the same cartridge overall length. If you significantly increase the projectile diameter, you have to shorten the cartridge case length and powder/propellant space. Please note that the Russian 20 X 99 and Japanese 20 X 94 use light (short) projectiles of 'standard' type. ONLY the Germans used the thin wall mine shell. The process of manufacturing the mine shell, while the concept is not difficult the actual execution is, was notable enough that the company's trademark symbol is a reference to the process. It is a similar process to making brass cartridge cases. Doing it in steel is a lot more difficult. Also please note that most cases taper, this aids extraction. Totally straight cases can cause problems and the higher the pressure the more problems. The Blow back guns usually operated at lower pressures than the locked breech guns.
From Tony Williams website. CANNON, MACHINE GUNS AND AMMUNITION
Please note that if you keep the same receiver length (a quick conversion) you are pretty much limited to the same cartridge overall length. If you significantly increase the projectile diameter, you have to shorten the cartridge case length and powder/propellant space. Please note that the Russian 20 X 99 and Japanese 20 X 94 use light (short) projectiles of 'standard' type. ONLY the Germans used the thin wall mine shell. The process of manufacturing the mine shell, while the concept is not difficult the actual execution is, was notable enough that the company's trademark symbol is a reference to the process. It is a similar process to making brass cartridge cases. Doing it in steel is a lot more difficult. Also please note that most cases taper, this aids extraction. Totally straight cases can cause problems and the higher the pressure the more problems. The Blow back guns usually operated at lower pressures than the locked breech guns.
- Thread starter
- #18
Agreed pretty much.
Hmm - while the MG 131 was out of question to receive the HE shell developed for the 15 mm cannon (body diameter was 17.1 mm at the widest part), the Italian Breda might be worth a try, with body diameter of 18.4 mm.
Granted, the Ho-5 wasn't that a powerful (79g shell at 750 m/s), but I don't think it was under-loaded. Please check out the quote in post #5 here.
For the 18mm, I agree that it should be around 700 m/s for the 100g shell, though I'd rather have an 80 g at 750+ m/s.
My idea was to either push the base .50 cartridge up to the biggest size of the shell that is practically possible, or to come out with a belt fed 20 mm cannon that is lighter than MG 151/20, let alone Hispano. The 17-18mm exploding ammo was well within the scope of any major armament/ammo producer in the world, even in late 1930s.
Oerlikon FF was probably the lightest recoiling gun, so comparing with it does not mean much. It would've recoiled less than Hispano or MG 151/20, that were frequently installed in or under fighter's wings.
Trying to have fighters with homogenous batteries - 4 light cannons, no HMGs.Bolded part is one of main benefits of the BMG - it was belt fed from the get go. The significantly lighter weight is another (both for gun and for ammo), and should remain so even when modified for a bit more heavier projectile.
The 0.5 inch Browning is likely to have been unattractive for many air forces.
Those air forces operating pre war designs such as the Me 109, Spitfire or the Russian fighters in particular had small aircraft with limited armament options.
The 20mm canon was the only way these aircraft could gain significant fire power as fitting enough 0.5 inch browning's wasn't practical due to the limited armament stations possible. The Soviets did quite well with motor canon, 20mm cowling guns, and wing root mounted guns and likely suited some other oddities such as wooden wings.
The MG131 was designed around the concept of creating a compact 13.2mm gun that could directly replace rifle calibre guns.
A M2/0.5 inch browning in many cases would not have fitted, probably not in the Me 109 cowling stations or the more streamlined or smaller German turrets.
The MG131 seems to have achieved its objective of replacing those guns while providing the destructive capability that had been lost to rifle calibre machine guns as armour increased.
Perhaps the Browning might have fitted easily in the wing stations of the Me 109 without the fitting gondolas but if that was the case the MG131 could have been fitted anyway.
I'd argue that the Spitfire might have done well with its 8 x 303 Browning's replaced by 8 x MG131 type guns.
Where the Germans might have benefitted from a 0.5 inch high velocity guns is in the commanders station of their tanks. The gun might have fitted there and given the problem the Germans had with air attack would surely have been a far more serious threat to VVS and allied aircraft than the traditional MG34 they used.
Explosive rounds were issued by the Luftwaffe on rifle calibre guns, their purpose was as a strike indicator. Because the Communist Soviet Government hadn't resigned the Hague Conventions or the Geneva conventions they started using explosive rounds in snipers guns and so these Luftwaffe rounds found themselves used by snipers on the Eastern front by the Heer as well.
One advantage of an explosive round is self destruct ability. The 20mm C38 round used by German FLAK had a self destruct. It's likely the MG151/20 and MG131 also had a self destruct ability. This is useful when you are firing above your own troops and population. Falling rounds was a big killer of civilians.
Those air forces operating pre war designs such as the Me 109, Spitfire or the Russian fighters in particular had small aircraft with limited armament options.
The 20mm canon was the only way these aircraft could gain significant fire power as fitting enough 0.5 inch browning's wasn't practical due to the limited armament stations possible. The Soviets did quite well with motor canon, 20mm cowling guns, and wing root mounted guns and likely suited some other oddities such as wooden wings.
The MG131 was designed around the concept of creating a compact 13.2mm gun that could directly replace rifle calibre guns.
A M2/0.5 inch browning in many cases would not have fitted, probably not in the Me 109 cowling stations or the more streamlined or smaller German turrets.
The MG131 seems to have achieved its objective of replacing those guns while providing the destructive capability that had been lost to rifle calibre machine guns as armour increased.
Perhaps the Browning might have fitted easily in the wing stations of the Me 109 without the fitting gondolas but if that was the case the MG131 could have been fitted anyway.
I'd argue that the Spitfire might have done well with its 8 x 303 Browning's replaced by 8 x MG131 type guns.
Where the Germans might have benefitted from a 0.5 inch high velocity guns is in the commanders station of their tanks. The gun might have fitted there and given the problem the Germans had with air attack would surely have been a far more serious threat to VVS and allied aircraft than the traditional MG34 they used.
Explosive rounds were issued by the Luftwaffe on rifle calibre guns, their purpose was as a strike indicator. Because the Communist Soviet Government hadn't resigned the Hague Conventions or the Geneva conventions they started using explosive rounds in snipers guns and so these Luftwaffe rounds found themselves used by snipers on the Eastern front by the Heer as well.
One advantage of an explosive round is self destruct ability. The 20mm C38 round used by German FLAK had a self destruct. It's likely the MG151/20 and MG131 also had a self destruct ability. This is useful when you are firing above your own troops and population. Falling rounds was a big killer of civilians.
Last edited:
Shortround6
Major General
Please look at the photograph again. For either the German 15mm shell or the Russian 20mm shell to fit the over length of the .50 cal Browning without lengthening the receiver you would have to cut the case back to the shoulder area (cut the neck off) and then for a new neck even if slight. This will have a significant impact on powder space. Both of these projectiles (and in in fact most projectiles) will extend to the base of the neck and many will extend to the base of the shoulder.
As an indication of what can happen with long projectiles extending into the powder are you have the German MG 151/20 ammo. Using a 'standard' type 115gram projectile (base in the shoulder area) it had a MV of 710m/s, switching to the M-Geschoss 92 gram projectile with the base in pretty much the same area the MV increased to 800m/s. Using the extra long 105 gram MX-Geschoss projectile with the extra length going into the powder space, the MV fell to 640ms/s.
Trying to use big bore projectiles in the German and BIJ (British-Italian-Japanese) 12.7mm runs into the same problem, they all used shorter (lighter) bullets than the American and Russian ( and French)12.7-13.2mm machineguns to begin with. Tring to use longer projectiles in the same over all round length cuts into the powder space. depending on projectile, it could cut in a lot.
Then you are back to diminishing returns, if you just scale down the design a 15mm fuse won't cost 75% (or even less) than a 20mm fuse. while you save on materiel you don't save on number of parts, you don't save much on machine time and you don't save on assembly time. Same on the cost of the whole projectile, materiel costs are down but labor cost won't follow in proportion.
While any major company or country could have made sub 20mm ammo it starts to become why? The ammo won't be that much cheaper per round. Most 20mm rounds of 115-30 gram projectile weight could deliver around 10 grams of HE. Some delivered less because they used the rear 20mm of a 80-90mm long projectile to hold a tracer element. The fuse used up 20-25mm of the front of the projectile.
The German 15mm 57 gram HE held 2.8 grams of HE but that was due not only to the small size but the fitting of a tracer element. Even without the tracer you were going to be very lucky indeed to get to 5 grams of HE. Needing two 15-16mm shells to deliver the same amount of explosive as a 20mm shell tends to skew the cost effectiveness. The Russian 20mm 97 gram shell held 6.1 grams of HE but was only 58mm in length, since it's fuse sucked up about the same 20-25mm as other peoples fuses this didn't leave much room for the HE even without the tracer. This points to not trying to use short 15-18mm projectiles in small cases to keep overall length down.
If you have to do a major modification to the gun (lengthen the receiver, bolt and bolt travel or make the bolt significantly larger in diameter) you might as well design a new case to do what you want rather than futz around trying to use old cases to save the case making tooling. That tooling will wind up being the least expensive part of the whole deal if you make a lot of ammo, as it wears out and needs replacing (the drawing dies and swages ) anyway.
As an indication of what can happen with long projectiles extending into the powder are you have the German MG 151/20 ammo. Using a 'standard' type 115gram projectile (base in the shoulder area) it had a MV of 710m/s, switching to the M-Geschoss 92 gram projectile with the base in pretty much the same area the MV increased to 800m/s. Using the extra long 105 gram MX-Geschoss projectile with the extra length going into the powder space, the MV fell to 640ms/s.
Trying to use big bore projectiles in the German and BIJ (British-Italian-Japanese) 12.7mm runs into the same problem, they all used shorter (lighter) bullets than the American and Russian ( and French)12.7-13.2mm machineguns to begin with. Tring to use longer projectiles in the same over all round length cuts into the powder space. depending on projectile, it could cut in a lot.
Then you are back to diminishing returns, if you just scale down the design a 15mm fuse won't cost 75% (or even less) than a 20mm fuse. while you save on materiel you don't save on number of parts, you don't save much on machine time and you don't save on assembly time. Same on the cost of the whole projectile, materiel costs are down but labor cost won't follow in proportion.
While any major company or country could have made sub 20mm ammo it starts to become why? The ammo won't be that much cheaper per round. Most 20mm rounds of 115-30 gram projectile weight could deliver around 10 grams of HE. Some delivered less because they used the rear 20mm of a 80-90mm long projectile to hold a tracer element. The fuse used up 20-25mm of the front of the projectile.
The German 15mm 57 gram HE held 2.8 grams of HE but that was due not only to the small size but the fitting of a tracer element. Even without the tracer you were going to be very lucky indeed to get to 5 grams of HE. Needing two 15-16mm shells to deliver the same amount of explosive as a 20mm shell tends to skew the cost effectiveness. The Russian 20mm 97 gram shell held 6.1 grams of HE but was only 58mm in length, since it's fuse sucked up about the same 20-25mm as other peoples fuses this didn't leave much room for the HE even without the tracer. This points to not trying to use short 15-18mm projectiles in small cases to keep overall length down.
If you have to do a major modification to the gun (lengthen the receiver, bolt and bolt travel or make the bolt significantly larger in diameter) you might as well design a new case to do what you want rather than futz around trying to use old cases to save the case making tooling. That tooling will wind up being the least expensive part of the whole deal if you make a lot of ammo, as it wears out and needs replacing (the drawing dies and swages ) anyway.
