Source?
Best synchronizable heavy machine gun of the war?
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P-39 Expert
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Disregard.
P-39 Expert
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The article has a Russian-English translation button in the upper right hand corner! Wonderful for those of us not fluent in Russian.
The Ho-103 is arguably a better aircraft gun than WW2 era US 0.50, as its lighter and fires faster, as it uses a lighter less powerful cartridge, which is the compromise.
WW2 era US 0.50 and Breda-Safat and Ho-103 (similar Browning designs) all lost alot ROF when synchronised. Thats part of the reason P-40 went from 2 x cowl 0.50 to 6 x wing 0.50s in -D model. Italy and Japan had gone from 7.7mm to 12.7mm so still had a net advantage.
For this thread the German MG131 is best synchronisable WW2 HMG for me, electric primer for realiable and high ROF when synchronised and powerful enough.
P-39 Expert
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Can you quantify?
the Breda-Safat when synchronized with the DB-601Aa in use on the Macchi C.202 fire a ~660 rpm when the engine run a 2400 rpm (Climb power), and ~690 rpm when the engine rus ant 2500 rpm (TO power) the Breda non synchronized is rated at 700 rpm
P-39 Expert
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Man, that seems like a really close tolerance 660/690 vs non synchronized 700rpm.
I don't have the sheet here where I had US 1930 tests (may even been 1926! where they got 400 rpm synchronised), it also had some reference to IT 12.7mm that I though was 400-500rpm.
Your earlier graph you posted shows the "synchronicity" of gun and prop that has a good science basis. Do you still have the .xls file, i would like to see how a 1200rpm gun would go?
These are generic wiki data but close enough,
Ho-103
Mass 23 kilograms (50 lb)
Barrel length 800 mm (31 in)
Cartridge 12.7×81mmSR
Rate of fire 900 rounds/min
Muzzle velocity 2,600 ft/s (780 m/s)
Ho-103 also got MA-102 adiabatic compression fuse HE rounds by 1944, these had 2.5x HE capacity of conventional "pin" fused HE 50 cal types rounds. Poor synchronised ROF due to Browning action?
50 M2 HB
Mass 38 kg (83 lb)
Barrel length 1,143 mm (45 in)
Cartridge 12.7×99mm
450–600 rounds/min (M2HB)
Muzzle velocity 2,910 ft/s (890 m/s)
50 BMG powerful round but big heavy gun. Tests in 1930's showed synchronised ROF was poor, but in peacetime it was only an academic flaw.
MG131
Mass 16.6 kg (37 lb)
Barrel length 550 mm (22 in)
Cartridge 13×64mmB
Rate of fire 900 round/min
Muzzle velocity 2,500 ft/s (750 m/s)
The MG131 is the lightest and smallest 0.50 that has good power, its synchronised advantage is an electric fired primer, so no metal firing pin with its own inertia, and especially synchronised with prop it may not even be a even firing rate which is another reason electrical primer is better. Of course the MG131 with electric primers and corresponding prop syncronisation system is higher technology and cost.
it is not a my work, i get it from a italian forum 150gct.it,
i've that for other combination, for example on C.200 with the Fiat A.74 engine they got ~590 rpm with the engine run at 2400 rpm (probably equivalent a "international rating") and ~620 at 2520 rpm (all out rating)
p.s. they did the graphs for all the italian "mass produced" fighters and the Breda Safat, probably you need some data on the MG for built the formula, i think if was applicable so easily (just up the max rpm) for all they do also for foreign weapons
Last edited:
Hi!
I'm not saying this is the best, though....
The Finns, together with the Swedes, copied Browning, and at the same time improved it.
Vkt 12 70 lkk/42
Weight of basic weapon: 24,25 kg
One barreled version with magazines: 56 kg
100 round belt weight: 13,2 kg
Firing speed: 1000-1100 rounds/minute
Bullet velocity: 700-835 m/s
Length of the rifling: 810 mm
Finnish-built Brownings for the Brewster Buffalo
I'm not saying this is the best, though....
The Finns, together with the Swedes, copied Browning, and at the same time improved it.
Vkt 12 70 lkk/42
Weight of basic weapon: 24,25 kg
One barreled version with magazines: 56 kg
100 round belt weight: 13,2 kg
Firing speed: 1000-1100 rounds/minute
Bullet velocity: 700-835 m/s
Length of the rifling: 810 mm
Finnish-built Brownings for the Brewster Buffalo
Shortround6
Major General
The Ho-103 was considerably lighter 23kg vs 29kg for the .50cal M2
It was also about 60% as powerful per shot, depending on exact round. The Ho-103 did use HE ammunition which made up part of that but not all.
The Ho-103 was supposed to fire at 900rpm unsynchronized, Some accounts say it was under 500rpm when synchronized. I don't know if later installations got better. Some accounts also say late war versions were derated (slowed down) other accounts say it wasn't
The US .50 fired at 600rpm unsynchronised in 1939-40 (if lucky) but in 1940 kits were issued and new production went to about 800rpm. Synchronized guns are reported to be between 4--500rpm in tests. I don't know if they got better later.
The US .50 cal ammo was larger and heavier.
The German MG 131 was even lighter, 17kg, it was also 10% less powerful than the Ho-103, it was rated at 900rpm (Unsynchronized?) and did use HE ammunition.
Please note the 12.7-13mm HE shells contained 0.8-1.2 grams of HE. A 20mm Hispano shell held about 10 grams.
It was also about 60% as powerful per shot, depending on exact round. The Ho-103 did use HE ammunition which made up part of that but not all.
The Ho-103 was supposed to fire at 900rpm unsynchronized, Some accounts say it was under 500rpm when synchronized. I don't know if later installations got better. Some accounts also say late war versions were derated (slowed down) other accounts say it wasn't
The US .50 fired at 600rpm unsynchronised in 1939-40 (if lucky) but in 1940 kits were issued and new production went to about 800rpm. Synchronized guns are reported to be between 4--500rpm in tests. I don't know if they got better later.
The US .50 cal ammo was larger and heavier.
The German MG 131 was even lighter, 17kg, it was also 10% less powerful than the Ho-103, it was rated at 900rpm (Unsynchronized?) and did use HE ammunition.
Please note the 12.7-13mm HE shells contained 0.8-1.2 grams of HE. A 20mm Hispano shell held about 10 grams.
Try to translate, source is here: VKT 12,70 LKk/42 | VL Myrsky II -entisöintiprojekti
VKT 12.70 LKk / 42 and other heavy machine Guns
Maker and model Caliber Weight Rate of fire Power Country of manufacture
Beresin UB 12.7 x 108 25 kg 800 ls / min 256 kW Soviet Union
Breda-SAFAT 12.7 x 81R 29 kg 700 ls / min 120 kW Italy
Colt MG53-2 12.7 x 99 29.2 kg 650 ls / min 156 kW United States
F.N. Caliber 13 13.2 x 99 24 kg 1.050 ls / min 273 kW Belgium
MG131 13 x 64 B 16.6 kg 900 ls / min 145 kW Germany
ShVAK 12.7 x 108R 42 kg 800 ls / min 209 kW Soviet Union
VKT 12.70 LKk / 42 12.7 x 99 25.7 kg 1,000 ls / min 255 kW Finland
Power is calculated from the Barrel of the gun. Power is affected by bullet weight, bullet flight speed, and rate of fire.
The Breda-SAFAT machine gun of the Fiat G.50 fighter was the least effective of the heavy machine guns, mainly due to the light bullet (33-35.4 g). The same "problem" is with Messerschmitt Bf 109 G-6 MG131 machine guns with bullets weighing 34-38.5 g. Instead, Colt suffered from a low rate of fire and the power was actually lower than shown in the table, as in Finland machine Guns were set to only 550 ls / min to save barrels, resulting in a power of about 132 kW.
Beres' UB (Berezina) was a remarkably powerful Weapon thanks to its heavy bullet (52 g), high starting speed (860 m / s) and high rate of fire (800 ls / min). No Wonder the Finns tried to install a Weapon in Morane and Curtis, for example! Unfortunately, there were other problems with the gun.
By comparison: the combined power of the four machine Guns of the VL Myrsky II without synchronization was 1.152 kW, the Brewster four Colt had practically 528 kW.
VKT 12.70 LKk / 42 and other heavy machine Guns
Maker and model Caliber Weight Rate of fire Power Country of manufacture
Beresin UB 12.7 x 108 25 kg 800 ls / min 256 kW Soviet Union
Breda-SAFAT 12.7 x 81R 29 kg 700 ls / min 120 kW Italy
Colt MG53-2 12.7 x 99 29.2 kg 650 ls / min 156 kW United States
F.N. Caliber 13 13.2 x 99 24 kg 1.050 ls / min 273 kW Belgium
MG131 13 x 64 B 16.6 kg 900 ls / min 145 kW Germany
ShVAK 12.7 x 108R 42 kg 800 ls / min 209 kW Soviet Union
VKT 12.70 LKk / 42 12.7 x 99 25.7 kg 1,000 ls / min 255 kW Finland
Power is calculated from the Barrel of the gun. Power is affected by bullet weight, bullet flight speed, and rate of fire.
The Breda-SAFAT machine gun of the Fiat G.50 fighter was the least effective of the heavy machine guns, mainly due to the light bullet (33-35.4 g). The same "problem" is with Messerschmitt Bf 109 G-6 MG131 machine guns with bullets weighing 34-38.5 g. Instead, Colt suffered from a low rate of fire and the power was actually lower than shown in the table, as in Finland machine Guns were set to only 550 ls / min to save barrels, resulting in a power of about 132 kW.
Beres' UB (Berezina) was a remarkably powerful Weapon thanks to its heavy bullet (52 g), high starting speed (860 m / s) and high rate of fire (800 ls / min). No Wonder the Finns tried to install a Weapon in Morane and Curtis, for example! Unfortunately, there were other problems with the gun.
By comparison: the combined power of the four machine Guns of the VL Myrsky II without synchronization was 1.152 kW, the Brewster four Colt had practically 528 kW.
Shortround6
Major General
The ratio of 590-620 is almost exactly that of 2400rpm to 2520rpm.
Lets remember that the gun was firing once for every several revolutions of the propeller Fiat A.74 at 2400rpm had the prop turning at 1600rpm. at 2520rpm the prop was turning at 1663rpm(?) Spec sheet for the A74 says 0.67 reduction gear but it might be 0.6666?
varsity07840
Airman 1st Class
- 176
- Jun 25, 2013
Melt? I think not. Burn out the rifling, yes.
swampyankee
Chief Master Sergeant
- 4,020
- Jun 25, 2013
Tony Williams has written a shortish article on synchronization; it's at his site. CANNON, MACHINE GUNS AND AMMUNITION. From what he wrote, it seems that the Germans, once they moved to electrical, vs percussion, primers had the least loss of rate of fire in synchronized installations, at about 10%. Constant speed props also made synchronization much easier.
Shortround6
Major General
We do have to be careful when using Wiki.
The Aircraft guns were NOT the .50 M2 HB.
The HB stands for Heavy Barrel and is the common ground gun.
The .US .50 cal went through a number of different models/versions and with the appropriate parts most could assembled on the same receiver.
The aircraft guns uses a 36in long barrel and not the 45in barrel of the ground guns. The early water cooled AA guns used by the Army and Navy (and tested by the British) used a 45in barrel. When they went for an air cooled barrel they increased the mass/weight of the barrel to permit longer firing times (still nowhere near what the water cooled guns could do).
The aircraft guns were expected to have the high speed air flow over the barrels and so their shorter barrels were also smaller in diameter.
I would also note that the velocity in Wiki is wrong for the aircraft guns and indeed for just about any .50 cal Browning in use before 1940 or so (like the British tests in the 20s-30s).
That velocity is correct for the long barrel using the M2 ball and later ammo that was introduced around 1940. The shorter barrel drops the velocity to about 2880fps. not a big deal.
HOWEVER. the M2 ball and later ammo used a different powder charger than the earlier ammo of the 1920s and 1930s with a much boosted velocity. The early ammo was around 2500fps with a slightly heavier bullet. Not only was this the ammo the British tested in often quoted tests but it is the velocity that most if not all of the British contract ammo was loaded to in the first few years of the war. It was also the velocity that batches of ammo that were sold to the British as "surplus" in 1940 were loaded to. (the US kept the newer stuff).
The British did get the high velocity stuff later under lend lease.
and once again, the US boosted the rate of fire of the unsynchronized M2 aircraft guns to around 800rpm ( I believe the manual says 750-850??)in late 1940. Existing guns could be modified with parts kits.
Barrel life of the .50 cal M2 is all over the place due, not only to cooling and different weight barrels but because the barrels themselves changed with time. Some got chrome plated bores and some got stellite liners (or partial liners?) that being the material valve seats are made of. A 1944-45 M2 is a rather different weapon than a 1939 M2 even if both are aircraft guns using externally similar barrels.
Weight of the aircraft guns was about 62-64 lbs for a bare gun. However you need firing solenoids and a charging system (air/electric/cable/???)and often a heating system.
Some of the other guns may or may not have accessories included in the weight.
The US .50 was a large, heavy gun with heavy ammo but it was not as bad as wiki makes it seem.
actually i've a 1:1.526 with the Fiat Hamilton propeller in monoplane fighter, the C.200 had, from the 25th, a Piaggio propeller i don't find data but i suppose is the same of Fiat propeller
