The Effectivness of 8 x.303s

[Glider]

From what I understand of him getting shot down didn't he make an ambitious attack on two 109's and get jumped, or something similar?

To be honest I don't remember much I was caught in a heavy downpour without a coat and dived into a book/coffee shop until the rain passed. So I didn't read all the book, just the bits that interested me.

 

[Waynos]

There was a documentary on TV where a group of archeologists were excavating a Spitfire and they thought it might be Baders. It wasn't, but they did identify it and it was very moving but as part of the investigation they went through combat records and this is where they found that he was almost certainly shot down by one of his own pilots as one of their reports described attacking a 109 and shooting its tail off while the pilot stayed with the aircraft a surprisingly long time. This corresponded exactly with what happened to Bader as after losing his tail he got his leg trapped and took ages to get out. Bader always claimed that was caused by a collision with a 109 which was also destroyed (possibly to protect his comrade, or to salve his own pride - who knows?)

By contrast no pilot of the Messerschmitt squadron concerned claimed any shoot down and the squadron itself lost no aircraft that day, contradicting both Bader and his pilot officer.

 

[renrich]

Bader flew in the BOB so he could not have been piloting a Spitfire V then, could he, Glider? I seem to remember that RAF pilots during the early stages of the war were taught to open fire at around 300 yards. The easiest shot was a no or very low deflection shot which meant either head on or from the six o clock position. A bomber from 300 yards would be a target which one could see fairly well, but think what a small target a 109 would look like at that range either head on or tail first. Three football fields or three sand wedges or a very long driver. Perhaps they felt they needed eight guns throw a lot of lead to have much chance for any hits?

 

[merlin]

Bader flew in the BOB so he could not have been piloting a Spitfire V then, could he, Glider?

No, in the Bob he flew a Hurricane with I think 242 Squadron.

His Spitfire V experience came a least a year later when he got shot down by 'friendly' fire (the TV evidence was very complelling), and made prisoner of war courtesy of the Luftwaffe. While he flew the aircraft although others had canon 0.303"s, he preferred all machine guns!

 

[Glider]

From what Merlin is saying, it looks as if I was looking at the book of the TV story the two match up pretty well.

 

[claidemore]

How about the effectiveness of 25 .303's?
A Home Guard unit (20-25 men) under Captain F.H.Clarke, armed with bolt action P14 .303 rifles shot down a Do17 on August 18, 1940. They fired 180 rds.
I wonder what their hit percentage was?

 

[Glider]

I read an account of a P40 Pilot flying low over the desert. He saw a German soldier have a go at him with a rifle, as he shot passed he gave the soldier the two finger salute. However the joke was on him as soon after his temperatures went through the roof due to a hit in the radiator. He crash landed and walked home.
One Bullet = one P40 not bad.

 

[HoHun]

Hi Claidemore,

>A Home Guard unit (20-25 men) under Captain F.H.Clarke, armed with bolt action P14 .303 rifles shot down a Do17 on August 18, 1940. They fired 180 rds.
>I wonder what their hit percentage was?

Pretty good, that much is sure For perspective: I once read that during the Pearl Harbour attack, 250,000 rounds of small arms ammunition were expended for every Japanese aircraft shot down.

Regards,

Henning (HoHun)

 

[renrich]

My latest "American Rifleman" has an article about a 50 BMG caliber rifle made in Serbia, of all places. Has a Mauser action but the interesting part of the article is the ballistics data. The ammo fired is a commercial brand with a 661 grain, I think, bullet at about 2900 feet per second. The muzzle energy is almost 12000 foot pounds. I had not seen ballistic data on the 50 BMG for a while but upon seeing that number I reflected on the following; I used to handload for a 26 inch barreled 270 Win with 150 grain spitzer bullet and it chronographed at 3000 feet per second. That is a little more velocity than one can get out of the 3006 or 303, I believe. The ME at that velocity is 2998 foot pounds and it has 1945 foot pounds at 300 yards. At any rate, if one says that the ballistics of the 3006 or the 303 or any other of the rifle caliber MGs used in WW2 were roughly the same, the eight MGs in the Spit or Hurri would give you 8x3000 ft pds of ME which equals 24000 foot pounds. Four 50 BMGs at roughly 12000 ft pds gives you 48000 foot pounds so you have twice as much energy with half the guns. Not only that but since the 50 cal bullet has a much better ballistic coefficient, it will retain it's velocity down range better that the 30 cal bullet which means that at 300 yards the disparity in energy will be even bigger. Comparing the rifle caliber MGs with the 50 BMG is kind of like comparing a chihuahua with a pit bull.

 

[Clay_Allison]

My latest "American Rifleman" has an article about a 50 BMG caliber rifle made in Serbia, of all places. Has a Mauser action but the interesting part of the article is the ballistics data. The ammo fired is a commercial brand with a 661 grain, I think, bullet at about 2900 feet per second. The muzzle energy is almost 12000 foot pounds. I had not seen ballistic data on the 50 BMG for a while but upon seeing that number I reflected on the following; I used to handload for a 26 inch barreled 270 Win with 150 grain spitzer bullet and it chronographed at 3000 feet per second. That is a little more velocity than one can get out of the 3006 or 303, I believe. The ME at that velocity is 2998 foot pounds and it has 1945 foot pounds at 300 yards. At any rate, if one says that the ballistics of the 3006 or the 303 or any other of the rifle caliber MGs used in WW2 were roughly the same, the eight MGs in the Spit or Hurri would give you 8x3000 ft pds of ME which equals 24000 foot pounds. Four 50 BMGs at roughly 12000 ft pds gives you 48000 foot pounds so you have twice as much energy with half the guns. Not only that but since the 50 cal bullet has a much better ballistic coefficient, it will retain it's velocity down range better that the 30 cal bullet which means that at 300 yards the disparity in energy will be even bigger. Comparing the rifle caliber MGs with the 50 BMG is kind of like comparing a chihuahua with a pit bull.

That is actually a bit light for a 50 BMG. The U.S. M2 military load uses a 720 grain FMJ-BT bullet at a MV of 2810 fps and ME of 12,600 ft. lbs.

 

[renrich]

Thanks Clay, I knew that the military bullet was in the 700 grain range but was too lazy to look it up. To clarify my post a little for those who read it and that aren't familiar with ballistics data, those figures are for one round from each gun or all eight or four guns firing one round. Of course, the average rifle caliber MG, unless it is firing through a prop arc will probably have a somewhat higher rate of fire than the 50 BMG but that higher number of bullets will not come close to canceling the energy advantage of the 50.

 

[merlin]

Another factor which hasn't been mentioned yet (unless I missed it) which certainly assisted the guns effectiveness - was the Dixon incedinary bullet.
The Dixon bullet (after Captain Dixon) is usually refered to as the de Wilde bullet (the name was kept to deceive the Germans).
At the start of the 'battle' the ratio of the Dixon bullet to the rest was low, but as production grew so to did its proportion to the rest - tracer and ball, and hence the destuctive power.

 

[HoHun]

Hi Merlin,

>At the start of the 'battle' the ratio of the Dixon bullet to the rest was low, but as production grew so to did its proportion to the rest - tracer and ball, and hence the destuctive power.

Hm, do you have any belting orders? I'm currently using a 1:1 belting of armour piercing and incendiary ammunition in my estimates of the 7.7 mm Browning firepower since these are the two ammunition types listed on Tony's site. Judging from your comment, that might be slightly optimistic.

(For the 12.7 mm Browning, I'm using armour-piercing incendiary exclusively, again because that's what Tony lists. For the 20 mm Hispano II, I'm using 1:1 armour piercing and incendiary. This might be optimistic in a 1940 context since apparently, a high proportion of ball ammunition was used early on, but I don't have any data on mass and muzzle velocity of ball ammunition I'm afraid.)

Regards,

Henning (HoHun)

 

[merlin]

The bullet was just in time to undergo its first operational test in the air battles over Dunkirk. Max Aitken, Douglas Bader, Al Deere, Victor Beamish, Colin Gray, Sailor Malan, and many others, testified to its magical properties and to the scramble there was amongst pilots to get their share of the bullet when, in the early days, it was is such short supply that only one gun out of eight could be loaded with it. A bit on an enemy plane by a Dixon bullet was immediately visible as a tiny burst of flame, making it invaluable for aiming purposes, and the incendiary qualities were dubbed again and again 'spectacular'. 'No aircraft that was built in the last war could stand up against it,' wrote Max Aitken, and R. M. 'Dickie' Milne wrote: 'It was a killer in comparison with other ammunition.'
A typical loading of the other seven was: armour-piercing in two, the old-type incendiary in another two (which gave a smoke-tracer effect), and ball in the other three.

This is an extract (though I think I paraphased it - from the original):

Barker, Ralph. THAT ETERNAL SUMMER Unknown Stories from the Battle of Britain, Chapter One, Collins, 1990, London.

Hope that helps.

 

[HoHun]

Hi Merlin,

>A typical loading of the other seven was: armour-piercing in two, the old-type incendiary in another two (which gave a smoke-tracer effect), and ball in the other three.

Thanks!

Do you have some data on the old-type incendiaries? I've found data on the ball ammunition (174 grains @ 2440 fps), but not on the incendiary rounds, where the chemical content proves particularly hard to find.

(Or are the incendiary rounds also listed as tracer rounds?)

With 2 armour piercing, 1 incendiary, 5 ball the effectiveness of the 8-gun battery is down to about 80% of what I originally calculated for 4 armour piercing, 4 incendiary. (I presume Tony's incendiary is the Dixon/de Wilde round ... do you have any data on its properties so I could check this?)

Regards,

Henning (HoHun)

 

[merlin]

Glad to help.
As it said in the above - the Dixon bullet only became available in time for Dunkirk, so what you read with Tony Williams (I think the official designation is incendiary Mk VII) is probably correct but for later - when supplies were plentiful.

Found another quote for you - from Deighton's 'Fighter' p.172/173

"In the First World War, some ace fighter pilots had become obsessional about the types of bullet they used; arranging them in the belts in certain sequences according to personal taste. The provision of eight separate identical guns made varying the ammunition very simple. A common mix was four guns with normal bullets, two with armour piercing and two with the new De Wilde incendiaries. This latter ammunition was very popular with the fighter pilots. Dowding said that they valued it far beyond its true worth but he was not taking into account the way that, although it had no tracer or smoke trail as previous incendiary bullets had, it made a bright yellow flash on impact. This proved a valuable aiming device. Believing that his pilots should have what they wanted, Dowding made special efforts to increase supplies of the De Wilde bullets. 'Sailor' Malan and Al Deere believed that the 250 yard harmonisation and De Wilde bullets made the difference between damaging enemy aircraft and destroying them."

I think the quote - shows how that during the BoB the ratio of Dixon rounds increased - but to what figure - haven't found a source yet to quote!

 

[ppopsie]

A very interesting subject. I have just looked over the posts;

Douglas Bader;
In a recording titled "Salute in Sound" which perhaps produced in 1968 with fine and various airplanes' engine noises, Douglas Bader himself mentioned about the Hurricane, something like; "The Hurricane was wonderfully maneouverable and a splendid gun platform in having four guns in each wing, in two BLOCKs" folllowed by a criticism on the Spitfire's dispersed gun arrangement in its wings.

On a Japanese Army aviation report;
In an instruction for the pilots made later in the war mentioned about the Lockheed P-38 for its concentrated firepower on the nose that the P-38s often start shooting at more than 1000m of range with high accuracy, and the IJA pilots shall be particularly careful about it. This was the case for the.50 guns however.

I therefore speculate not only the number of the guns but the way they were arranged had some infulences on the firepower of the each fighter types.

Aiming of the guns having different characteristics each;
An ex-Zero officer pilot who had flown from Kagoshima area on the final days of the war gave us a lecture few years ago. During which he said had troubled with shooting the different types of the guns with single gun sight; 20mm Oericon and 7.7mm machine guns. Of course these had different ballistics and effective ranges. I was even asked by him that "Have you ever heard or read the same kind of story?"

 

[HoHun]

Hi Merlin,

>As it said in the above - the Dixon bullet only became available in time for Dunkirk, so what you read with Tony Williams (I think the official designation is incendiary Mk VII) is probably correct but for later - when supplies were plentiful.

To defend Tony, he just listed the ammunition types - the decision to calculate effectiveness for a 1:1 (or 4:4) mix was mine.

>Found another quote for you - from Deighton's 'Fighter' p.172/173

Ah, that's a good one. I read that a long time ago, and it really stuck to my mind. Considering that pilots of all nations were warned against relying too much on tracers, the Dixon/de Wilde ammunition must have had additional value over its incendiary effect due to showing that the impacts are on target. From what I read, tracers would often create the illusion of being on target when in reality they were missing. (The Luftwaffe actually designed a special "observation round" for exactly that purpose. It was mostly used with flexible defensive positions on bombers, though.)

>A common mix was four guns with normal bullets, two with armour piercing and two with the new De Wilde incendiaries. This latter ammunition was very popular with the fighter pilots.

Excellent, this 42 Ball:AP:I mix would still yield 86% of the 4:4 AP:I mix' effectiveness Accordingly, my above estimates should not be too far off. (It's not like the comparison against 12.7 mm or 20 mm guns was particularly close-run to begin with.)

While we're at it, do you happen to have any data on the 20 mm "ball" (actually, steel) rounds of the Hispano II? From Tony's work, it seems that these were used initially with the Hispano cannon because other rounds were not yet available in numbers, and as we're talking about a Battle of Britain context here, it might be better to figure in the lower effectiveness of these rounds too.

Regards,

Henning (HoHun)

 

[HoHun]

Hi Ppopsie,

>I therefore speculate not only the number of the guns but the way they were arranged had some infulences on the firepower of the each fighter types.

Absolutely - centreline guns had much better accuracy both due to absence of convergence/divergence geometry and also due to being stiffer than wing mounts.

>During which he said had troubled with shooting the different types of the guns with single gun sight; 20mm Oericon and 7.7mm machine guns. Of course these had different ballistics and effective ranges. I was even asked by him that "Have you ever heard or read the same kind of story?"

The Fw 190 pilots testing the type criticized the early gun button wiring which triggered the machine guns on button "A" (the trigger on front of the stick) and all four cannon on button "B" (the pushbutton on top of the stick). They preferred to have machine guns and wing root cannon on button "A" and wing cannon on button "B".

I don't have data on the battery of the Zero, but below is a diagram for the similar battery of the Me 109E-4 with two MG 17 on the cowl and two MG FF/M (similar to the Japanese Oerlikon) in the wings. Note that the late-war Oerlikon guns used by the Japanese had a higher muzzle velocity, if I recall correctly. Against a fighter-sized target, the MG FF/M gave a maximum "point blank" range of just 300 m. The centre of the MG 17 pattern is deliberately adjusted to a different distance (400 m), and this indicates that the MG 17 was expected to be used for somewhat longer ranges than the MG FF/M. Accordingly, both sets of weapons could not necessarily be expected to converge at shorter ranges, but that clearly was a conscious trade-off here. As the MG FF/M had about 10 times the firepower of the MG 17, it didn't matter much if the MG 17 missed the target at short ranges if the MG FF/M hit.

(The animated GIF shows the pattern in 100 m steps, beginning at 100 m and going out to 1000 m.)

Regards,

Henning (HoHun)

 

[ppopsie]

Thanks HoHun-sama,

I read war stories written by other Zero pilots. Saburo Sakai preferred the 7.7mm machine guns on the nose to the 20mm Oelikons in the wings, for the former's greater firing rate. This implies he must've done shooting at close ranges. I think it was about the case of A6M2, on early days of the air combats in Rabaul area.

Another example being Tsutomu Iwai's. When he shoot an enemy plane, he deliberately spread the line of shooting by shoving the control stick a little. He said it worked well to get effective hits on the enemy plane. I think this was for the A6M5 he flew later in the war.

8 gun Hurricanes; this is an excellent wartime story was told by a Russian naval ace pilot Nikolay Gerasimovich Golodnikov. He talked about how the eight machine guns on the Hurricane worked, on the part 1, about 4/5 from the top.
Part 1

I understand the examples I listed are not based on any of quantitive data but can be used to some extent explaining the theory; fire more bullets per second.