Was .303 the smallest calibre mg used in WW2 aircraft?

BlackSheep

Senior Airman
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I’ve never heard of a smaller round being used, even in WW1, excluding the handguns which got the whole thing started, but, my word is far from final on the matter.
 

wlewisiii

Staff Sergeant
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Mar 5, 2009
I had thought that I read of 7x57 being used in South America where it was a common rifle/MG cartridge, but I am not finding it anywhere.
 

Greyman

Tech Sergeant
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Jan 31, 2009
There may have been some 6.5mm armed aircraft in use early in the war.

Maybe some 6.5mm Madsens in China? The Swedes had some 6.5mm FN Brownings if that counts ...

The French 7.5mm would certainly be the smallest of the widely-used rifle rounds.
 

Shortround6

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That is for the nominal caliber.
The real caliber of the french 7,5 X 54 round model 1929C is 7,84 mm.
A lot of the 7.5mm to 7.7mm stuff was actually .308 to .312 bullet diameter. Which is enough to win a bar bet but not any real difference in power.
Some countries used the bore diameter and some countries used the diameter to the bottom of the grooves which screws things up.
American .30-06 used a .300 bore and a .308 groove and used .308 bullets
French 7.5mm used a .298 bore and a .309 groove and ????bullets.
reloading manuals just use a .308 bullet.
War time (or pre war) barrels had a wider allowable tolerance. Groove diameter could vary .002-.003 from one end of a barrel to the other.

Power of the cartridges depends on the bullet weight times velocity squared.
Bullets went from 8.8 grams to 12.1 grams.
Velocity went from 747m/s to 900m/s (?) so there was a lot of crossover.

Anthony Williams lists the 6.5 X 55 Swedish in his book but the Swedes also used the 8 X 63 round in their Browning's

As far as the 5.56 goes, there were only 2 US cartridge's that were in that catagory and they (and any European rounds) were specialized hunting rounds. The .22 Hornet was too small for military use (used in SAC survival rifles in the 1950s) the .220 Swift which was at the other end of the spectrum considerably more powerful than the 5.56 NATO. It had a reputation for burning up barrels and in fact was the first rifle barrel that Winchester made out of stainless steel to try for longer barrel life. No military wanted any part of getting involved with that.
 

Shortround6

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I would note that the British, Italians and Japanese Navy all used the same ammo (or at least it would fire in each others guns) so the ammo 'power' is actually pretty equal.
The Russian ammo was bit more powerful (around 10%) and the American and German ammo lead the pack.

For perspective the Italian and Japanese Army 12.7mm ammo was about times as power as the .303/7.7mm per cartridge and German (and Japanese navy flexible gun) 13mm ammo was a few percent below that.

Rate of fire and feed system/s were much more important than the power of the different Rifle Caliber Machine Gun (RCMG)cartridges.
 

BlackSheep

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May 31, 2018
I would note that the British, Italians and Japanese Navy all used the same ammo (or at least it would fire in each others guns) so the ammo 'power' is actually pretty equal.
The Russian ammo was bit more powerful (around 10%) and the American and German ammo lead the pack.

For perspective the Italian and Japanese Army 12.7mm ammo was about times as power as the .303/7.7mm per cartridge and German (and Japanese navy flexible gun) 13mm ammo was a few percent below that.

Rate of fire and feed system/s were much more important than the power of the different Rifle Caliber Machine Gun (RCMG)cartridges.
I agree 100%
Wasn’t the ROF of four 303s in a bomber turret a big reason the RAF cited for not up-gunning to 50 cal, early in the war?
 

Greyman

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The big reason seems to be Frazer-Nash and Boulton Paul not being able to produce an acceptable .5-inch turret.

Harris:

I have always maintained that the defensive armament of our heavy bombers was insufficient. A continuous flow of recommendations (some dating since, 1940), have been submitted to the Air Ministry, covering such aspects as the vital need for improved view from turrets, the provision of four instead of two guns in dorsal and tail positions, and the need for larger calibre guns was continually stressed.

... it will be seen that in so far as turrets and guns were concerned, very little had been done between February, 1942, and May, 1945, to improve the defensive armament of heavy bombers and, apart from the Rose turret, no real progress had been made in producing for Bomber Command a turret which possessed the characteristics laid down by this Command in 1942. The Air Ministry had under development the F.N. 82 and B.P. "D" tail turrets, each armed with two 0·5-in. guns, and the Bristol B.17 mid-upper turret with two 20-mm. cannon, but none of these turrets became available for use in Bomber Command during the war against Germany. Throughout, those responsible for turret design and production displayed an extraordinary disregard of the requirements of the Command.
 

PAT303

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Personally I don't think it's makes any difference what guns you had, the waist gunners in American bombers were trying to hit a fighter closing in at 350 plus miles an hour while traveling at 200 plus miles an hour with a pindle mounted .50, do you really think they had any chance of accurately tracking ranging and leading a fighter enough to make one gun better than another?, same for rear seat gunners in torpedo/dive bombers, I believe loading lots of tracer would be a better deterrent than the size of the bullets.
 

Greg Boeser

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The rear gunner makes sense, because an attack from the rear means an almost zero deflection shot.
Waist gunners were at best for morale.
Of course, you can make the argument that deleting the waist gunners frees up about 1000 lbs for bombs or fuel.
 

Shortround6

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Once the escort fighters showed up (or a while after) the Americans started leaving several men (waist gunners) at home. The actually weren't contributing very much, there are some charts around showing dispersions from the different gun mounts and pretty much hitting the intended target with a waist gun was pretty much a few percentage points above pure accident. I can't remember the ball figures but they weren't that good either, which was surprising for a power turret but that is a rather cramped position. Not sure if they started leaving ball gunners at home very late in war.
On the B-17s they may have taken out the radio operator's gun ( sticking out the top) but since since you couldn't leave the radio operator home you might not same that much, and it might have been good for the radio operators morale. ;)

On the US rear seat gunners, there was some debate about using a single .50 or a pair of .30s. Some gunners claimed the paired .30s were easier to manhandle in the slipstream.
But that may depend of the configuration of the canopy and ability to act as a wind break.

Some soviet aircraft did somewhat better
Pe-2Ears-735x413.png

the wind vane turned with the "turret" and was suppose to balance the gun barrel with the force of wind. Swing the gun to the right and vane swung out to the left.
Italians did somewhat the same thing.
 

Shortround6

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I believe loading lots of tracer would be a better deterrent than the size of the bullets.
US tried to develop a tracer that showed up better from the front. Standard tracer isn't all that visible from the direction of the people being shot at, at least in daylight.

For the British Sticking a pair of .303 Brownings in with belts was probably better than a pair of Vickers "K" guns with 96 shot drums. Of course that may depend on the belt boxes.
89th-10-7_005.jpg

I think later on they put the belt boxes (larger?) under the mount and not didn't use small belts on the actually mount.
The British 4 gun tail turrets ran the ammo belts from the turret into the waist of the aircraft and they could fire thousands of rounds without reloading.


I thin
 

PAT303

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If you read up on the Falklands war the Argentinian pilots were distracted by MAG 58 tracer rounds after they were bolted onto every available railing, Luftwaffe pilots also said they took notice of them as did American pilots over Vietnam.
 

Snowygrouch

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Brits didn’t have 50 cal turrets or cannon turrets for a combination of reasons. I think what Harris said quoted above is basically nonsense. (As In I’m sure he did say that but it doesn’t tally with the air ministry files). There was a big supply issue early on with 50s and the cannon turrets were so heavy it necessitated reducing the bomb load to the level where it was calculated that you’d need to fly more planes over the target and you’d end up with the same aircrew losses anyway. I’m not 100 percent sure I agree with all the reasoning but that was how it was discussed at the time.
 

peiper

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Personally I don't think it's makes any difference what guns you had, the waist gunners in American bombers were trying to hit a fighter closing in at 350 plus miles an hour while traveling at 200 plus miles an hour with a pindle mounted .50, do you really think they had any chance of accurately tracking ranging and leading a fighter enough to make one gun better than another?, same for rear seat gunners in torpedo/dive bombers, I believe loading lots of tracer would be a better deterrent than the size of the bullets.
good call......as I've said on other forums--a mediocre weapon in the hands of trained, motivated troops is better than a great weapon in poorly trained, unmotivated troops.......training, experience etc is a great factor in weapon effectiveness
..also, combined arms training increases the effectiveness of different weapons/systems/etc
 

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