Why no heavier RAF machine gun calibres? (2 Viewers)

[Clayton Magnet]

I continue to be amazed at the extensive use of the retrospectroscope in any and all discussions of earlier RAF adoption of the 50 cal.

'Merica used fifty cals, therefore everyone else was obviously behind the times. If Lockheed had any sense, they would have put 8 fifty's in the F-22's wings. The trend towards 20 and 30mm cannons in fighters, is just Europe trying to force metric on everyone

 

[buffnut453]

'Merica used fifty cals, therefore everyone else was obviously behind the times. If Lockheed had any sense, they would have put 8 fifty's in the F-22's wings. The trend towards 20 and 30mm cannons in fighters, is just Europe trying to force metric on everyone

Yep...which is where the retrospectroscope comes in. The US didn't have 50 cals in its fighters until late 1940 at the earliest and didn't get them working reliably until late 1942. Don't get me wrong, I'm a huge fan of the Ma Deuce...but the rather snide finger-pointing by many simply refuses to acknowledge the development timeline for that weapon or the operational imperatives at play before the US entered WW2.

 

[pbehn]

Yep...which is where the retrospectroscope comes in. The US didn't have 50 cals in its fighters until late 1940 at the earliest and didn't get them working reliably until late 1942. Don't get me wrong, I'm a huge fan of the Ma Deuce...but the rather snide finger-pointing by many simply refuses to acknowledge the development timeline for that weapon or the operational imperatives at play before the US entered WW2.

Issues continued with 50 Cals into 1943. The P51B had some minor issues which the British and Americans worked on. The solution was similar to the solution found with British cannon because the problem was the same not with the actual gun but smoothly feeding in the ammunition at high "G".

 

[Shortround6]

The Boeing P-12s were supposed to have carried one .50 and one .30. How often this was actually done? Or is it a oft repeated tale in the .50 cal Legend?
A very quick google search shows no pictures but that is not definitive ether way.
I seem to remember a statement about replacing the .50 cal for gunnery training because the ammo was cheaper but that also could be hanger talk.

 

[PAT303]

And cowl-mounted weapons have a lower rate of fire than the same weapon in a wing installation. Even on the existing timelines, wing installation of the M2 proved problematic in wing installations until the latter half of 1942.

I continue to be amazed at the extensive use of the retrospectroscope in any and all discussions of earlier RAF adoption of the 50 cal. The 303 was perfectly adequate against aircraft that were in service as late as 1939. Heavier calibres only become truly necessary when armour and self-sealing fuel tanks become commonplace, or to counter the large-scale deployment of bigger 4-engined bombers.

I continue to be amazed at people who refuse to understand WHY the 8 .303's were fitted, it's because most pilots couldn't actually hit anything in combat so to make up for the lack of accuracy they simply threw more bullets, they even developed the "Dowding Spread" to produce a shot gun pattern of bullets to try and increase hits.

 

[PAT303]

Issues continued with 50 Cals into 1943. The P51B had some minor issues which the British and Americans worked on. The solution was similar to the solution found with British cannon because the problem was the same not with the actual gun but smoothly feeding in the ammunition at high "G".

From what I have read the feeding was the issue with all HMG's and Cannons in the early war years, G forces on the belts caused all types of issue's.

 

[Alan Stevens]

I continue to be amazed at people who refuse to understand WHY the 8 .303's were fitted, it's because most pilots couldn't actually hit anything in combat so to make up for the lack of accuracy they simply threw more bullets, they even developed the "Dowding Spread" to produce a shot gun pattern of bullets to try and increase hits.

Wouldn't that many 30 cal slugs make a really bad day for anybody?

 

[ThomasP]

From another thread:

In an interview a long time after the war, Gunther Rall commented on the quality of different nation's aircraft. When asked what he thought the best fighter weapon of the war was, his reply (I am paraphrasing here because I do not have a transcript of the interview to hand) went something like this. "If you were to pick only one type of weapon to carry the Americans probably had the best balance in the .50 cal Browning. But people who disparage the British with their .303 cal MGs are incorrect. When there are 8 or 12 of them firing, you would end up with a hole in every part of the airplane...including you."

 

[PAT303]

Wouldn't that many 30 cal slugs make a really bad day for anybody?

I wouldn't want to be on the receiving end of a 2 second burst

 

[PAT303]

From another thread:

In an interview a long time after the war, Gunther Rall commented on the quality of different nation's aircraft. When asked what he thought the best fighter weapon of the war was, his reply (I am paraphrasing here because I do not have a transcript of the interview to hand) went something like this. "If you were to pick only one type of weapon to carry the Americans probably had the best balance in the .50 cal Browning. But people who disparage the British with their .303 cal MGs are incorrect. When there are 8 or 12 of them firing, you would end up with a hole in every part of the airplane...including you."

Many of the RAF pilots like Johnny Johnson wanted four Hispano's.

 

[pbehn]

Many of the RAF pilots like Johnny Johnson wanted four Hispano's.

From what I gathered from Bungays "The Mos Dangerous Enemy" was that, it was perception not fact in the BoB era. RAF pilots were getting hit by canon and so wanted them. The 8 Mgs of a Spitfire or Hurricane sometimes seemed to have no effect. But they didnt see what happened later, some ditched some made forced landings and many landed but never took off again, they took a heavy toll on the crews too.

 

[PAT303]

From what I gathered from Bungays "The Mos Dangerous Enemy" was that, it was perception not fact in the BoB era. RAF pilots were getting hit by canon and so wanted them. The 8 Mgs of a Spitfire or Hurricane sometimes seemed to have no effect. But they didnt see what happened later, some ditched some made forced landings and many landed but never took off again, they took a heavy toll on the crews too.

This pilot probably complained that the .303's had no effect but the rounds are clearly going behind the He111, 300 plus yards crossing left to right on a better than 90 degree deflection is a tough shot.

 

[Thumpalumpacus]

View attachment 808155
This pilot probably complained that the .303's had no effect but the rounds are clearly going behind the He111, 300 plus yards crossing left to right on a better than 90 degree deflection is a tough shot.

That He-111 cockpit doesn't look like a happy place. Even so, your critique in mind, is that the fault of the gun or the shooter? Definitely a tough shot, no argument there.

 

[Marcel]

I continue to be amazed at the extensive use of the retrospectroscope in any and all discussions of earlier RAF adoption of the 50 cal. The 303 was perfectly adequate against aircraft that were in service as late as 1939.

Robert Stanford Tuck was disagreeing on you there in 1940, though.

 

[PAT303]

That He-111 cockpit doesn't look like a happy place. Even so, your critique in mind, is that the fault of the gun or the shooter? Definitely a tough shot, no argument there.

It's was simply where air forces were in 1940, basic gun sights, minimal gunnery training and tactics. I wish I could find a report I had that was compiled after wrecks from both sides were inspected during the BoB, it showed the most successful attacks were from directly behind the target at close range after examination of the bullet strikes.
If you look at the above photo the 109's slower 20mm shells would be even further behind the 111 in that situation so yes they had more hitting power but first you have to make the hit.

 

[buffnut453]

Robert Stanford Tuck was disagreeing on you there in 1940, though.

Yes, because technology changed rapidly during wartime...and why I identified 1939 as the cut-off for 303 being an optimal weapon. However, the Browning M2 still wasn't ready for primetime, at least in wing installations, in 1940. The RAF decided to start fielding 20mm cannon in fighters in 1940 and I've never argued that the move was wrong. With increasing use of armour plate, the RAF needed more firepower in its fighters, not least from a range perspective. I also don't disagree that he Browning M2 was a great balance between punching weight and firing duration.

My frustration is with those who equate the M2's capabilities in 1943 with how it was performing in 1939 or 1940. On occasion, that mindset tends to diminish the performance of the 303: the term "paint scratchers" has been used which, even in 1940, was definitely not the case.

 

[Admiral Beez]

The Nash & Thompson rear turret of the Lancaster Mk.VII was fitted with twin .50s

Was a four .50 cal manned rear turret ever tried before the B-52? It would be a beast.

Here's the M45 Quadmount for scale.


View: https://www.youtube.com/watch?v=jfLEq2PrgME

 

[Shortround6]

Yes, because technology changed rapidly during wartime...and why I identified 1939 as the cut-off for 303 being an optimal weapon. However, the Browning M2 still wasn't ready for primetime, at least in wing installations, in 1940. The RAF decided to start fielding 20mm cannon in fighters in 1940 and I've never argued that the move was wrong. With increasing use of armour plate, the RAF needed more firepower in its fighters, not least from a range perspective. I also don't disagree that he Browning M2 was a great balance between punching weight and firing duration.

There was am overlap of effectiveness which confused things even between the 20mm and the .303 ammo. The .303 was not equipped with anywhere near it's optimum ammo During the BoB. They did not have enough of both AP and Incendiary ammo. Increasing either/both to about double what they were using in the BoB would make at least a noticeable impact.
The 20mm guns in Spitfires had problems until they got the C wing with the belt feed. There was also a problem with the fuses in the early ammo being much too sensitive and exploding on impact with the aircraft skin and not penetrating, solve in short term by mixing in solid (or hollow) inert training rounds which would penetrate quite a bit but not do anything else. I don't know when they got the fuse thing straightened out.
One does wonder what a Hurricane IIB firing 5 guns with AP and 5 guns with incendiary and 2 guns with tracer would have done to German bombers in mid 1941 compared to the 2 guns with AP and one or two guns (if lucky) with incendiary used in the BoB.

My frustration is with those who equate the M2's capabilities in 1943 with how it was performing in 1939 or 1940. On occasion, that mindset tends to diminish the performance of the 303: the term "paint scratchers" has been used which, even in 1940, was definitely not the case.

Preaching to the Choir here Buffnut453 .
British didn't like American .50 cal incendiary bullets in 1940/41 and didn't use them. Which pretty much left them with with AP, Ball and tracers. And as we both know, the 1940/41 British .50 cal ammo had about 300fps less velocity which meant it had a lot less punch than the later US rounds. It was better than the British, Italian, Japanese .5/12.7 but not even the stuff the Americans used at Midway (or before?).
This is when the British could even get the .50 cal guns to fire even in the nose of a Tomohawk in the summer of 1941.

 

[PAT303]

There was am overlap of effectiveness which confused things even between the 20mm and the .303 ammo. The .303 was not equipped with anywhere near it's optimum ammo During the BoB. They did not have enough of both AP and Incendiary ammo. Increasing either/both to about double what they were using in the BoB would make at least a noticeable impact.
The 20mm guns in Spitfires had problems until they got the C wing with the belt feed. There was also a problem with the fuses in the early ammo being much too sensitive and exploding on impact with the aircraft skin and not penetrating, solve in short term by mixing in solid (or hollow) inert training rounds which would penetrate quite a bit but not do anything else. I don't know when they got the fuse thing straightened out.
One does wonder what a Hurricane IIB firing 5 guns with AP and 5 guns with incendiary and 2 guns with tracer would have done to German bombers in mid 1941 compared to the 2 guns with AP and one or two guns (if lucky) with incendiary used in the BoB.

Preaching to the Choir here Buffnut453 .
British didn't like American .50 cal incendiary bullets in 1940/41 and didn't use them. Which pretty much left them with with AP, Ball and tracers. And as we both know, the 1940/41 British .50 cal ammo had about 300fps less velocity which meant it had a lot less punch than the later US rounds. It was better than the British, Italian, Japanese .5/12.7 but not even the stuff the Americans used at Midway (or before?).
This is when the British could even get the .50 cal guns to fire even in the nose of a Tomohawk in the summer of 1941.

All good points, RAF fighters in the BoB used a lot of standard Mk7 cup and core ball ammunition which would have been the standard load out for for .50 also in the BoB if it was used which isn't much good for setting planes on fire, the .50 AP rounds also tumbled after impact further reducing their effectiveness, as for the 20mm they had fusing issue's that weren't sorted until after the BoB, the Hispano's usually didn't go off and the MG FF's graze fuse detonated too early which tore impressive holes in the outer skin while leaving the internal structure secure.

 

[Clayton Magnet]

I also don't disagree that he Browning M2 was a great balance between punching weight and firing duration.

The Browning M2 indeed did strike a good balance between punching weight and firing duration.
However, it was a decidedly poor option when total weight of installation was considered, especially for fighter aircraft. Just about any of the major 20mm auto cannons used in the conflict provided a more efficient balance between destructive potential, and aircraft performance penalty due to the weight of the installation.

But of course, only the Ma Deuce had the magical ability to saw an aircrafts wings off, or destroy a Tiger tank from below.