Explosive rounds

[Haztoys]

How do explosive rounds and shells work.......... ...I'm sure theres many ways of doing it ...Always wanted to know..Thanks

 

[kool kitty89]

Well there's this Shell (projectile) - Wikipedia, the free encyclopedia
Komet weapons: MK 108 cannon


And on guns: The WWII Fighter Gun Debate: Gun Tables


And an interesting note on unfuzed HE rounds (using sensitive explosives) particularly used by the Japanese, hence why they managed to devise a fairly practical 7.7 mm (.303) HE round:
.303 British - Wikipedia, the free encyclopedia

However using such fillers as straight PETN for the main charge in such small rounds is dangerous and can risk explosion in the gun (either by the shock of firing, overheating of the gun, damage or fault to the round/gun, or a mix of these) or detonation of the magazine from a hit from enemy fire.

Although PETN (penthrite, or nitropenta) was one of the main HE fillers for German HE rounds.

 

[merlin]

I went to the Wiki link to British 0.303", and I amazed at the lack of reference to the Dixon incendary ammunition (usually referred to as de Wilde).

Captain Dixon (responsible for small arms ammunition) was entrusted to handle to the conversion of the de Wilde ammunition to British manufacturing processes. Unfortunately, the was hand-made with no quantifiable measures of the ingredients - i.e. a pinch of this followed by a pinch of that.

Hence, Dixon (without instruction or permission) found his own solution. And, just in time too, as without such ammo IMO the 0.303's wouldn't have been as effective as there were (and 'effective' is debateable anyway with so many damage aircraft making it back).

The Dixon design, kept the name 'de Wilde' to lull the Germans into a false sense of sercurity because they new all about. the 'de Wilde' weren't too happy - but the payment they recieved satisfied them. And the US also benefitted as the design was virtually given to them as reverse lend-lease.

 

[kool kitty89]

Didn't the Dixon round become the Mk.VI incendiary round? (which was then copied and simpified for US .30-06 and .50 BMG and then copied again by the Brits to create the Mk.VII incendiary)

From Tony Williams: 1.JmA.net :: View topic - DeWilde ammunition

Posted: Apr 22, 2007 10:23 am Post subject:

--------------------------------------------------------------------------------

Sorry for the delay, I only have the time to make occasional visits!

The design of effective small-calibre incendiary bullets was difficult. A lot of work was done in WW1, initially for shooting down hydrogen-filled artillery spotting balloons and airships, but they all had disadvantages. The one which the RAF retained into WW2 was the Mk IV (Buckingham) incendiary/tracer, which started to burn on firing and left a smoke trail.

A Belgian, De Wilde, invented what appeared to be a much more effective bullet. I summarise this in the article on the armament of the Battle of Britain fighters on my site:

"The incendiary ammunition was also variable in performance. Comparative British tests of British .303" and German 7.92 mm incendiary ammunition against the self-sealing wing tanks in the Blenheim, also fired from 200 yards (180m) astern, revealed that the .303" B. Mk IV incendiary tracer (based on the First World War Buckingham design – it was ignited on firing and burned on its way to the target) and the 7.92 mm were about equal, each setting the tanks alight with about one in ten shots fired. The B. Mk VI 'De Wilde' incendiary (named after the original Belgian inventor but in fact completely redesigned by Major Dixon), which contained 0.5 grams of SR 365 (a composition including barium nitrate which ignited on impact with the target) was twice as effective as these, scoring one in five.

The 'De Wilde' bullets were first issued in June 1940 and tested operationally in the air battles over Dunkirk. Their improved effectiveness, coupled with the fact that the flash on impact indicated that the shooting was on target, was much appreciated by the fighter pilots. It was at first in short supply, and the initial RAF fighter loading was three guns loaded with ball, two with AP, two with Mk IV incendiary tracer and one with Mk VI incendiary. Another source for the Battle of Britain armament gives four guns with ball, two with AP and two with incendiaries (presumably Mk VI) with four of the last 25 rounds being tracer (presumably Mk IV incendiary/tracer) to tell the pilot he was running out of ammunition. It is not clear why ball was used at all; presumably there was a shortage of the more effective loadings. (By 1942 the standard loading for fixed .303s was half loaded with AP and half with incendiary.)

The Mk VI was good enough that the USA copied it, in simplified form, for both their .30 and .50 aircraft ammo. The British then copied back the simplified design as the Mk VII.

 

[merlin]

Yes, I agree with the Tony Williams extract - though I thought the Dixon/'de Wilde' bullet was more effective than 'twice' that of the previous incendary/tracer bullets.
I'd have to re-read the precise I did, of an article on Dixon, a by E.C.R. Baker.

I re-read the wiki reference - and to me (judging by the years it quoted in relation to the Mk No's), it only seemed to refer to British Army 0.303 ammo!

Although Tony, referred to Major Dixon (he got rapid promotion during the war in recognition of his services), I think it a travesty that 'de Wilde' is still used in publications - often without the appostrophy. It's almost, as if the German WW1 ballons were referred to as Montgolfier ballon rather than a Zepplin!!

 

[kool kitty89]

There's some mention of the Mk.6/7 incendiaries (Mk.VI/VII), but none specifically about Dixon (or De Wilde)

and armour-piercing cartridges were introduced during 1915. Explosive bullets of the Pomeroy design as Mark VII.Y in 1916.

Several incendiaries were privately developed from 1914 to counter the Zeppelin threat, but none were approved until the Brock design late in 1916 as BIK Mark VII.K [7] Wing Cmdr. Brock RNVR was a member of the Brock fireworks-making family.

These rounds were extensively developed over the years and saw several Mark numbers. The last tracer round introduced into British service was the G Mark 8 in 1945, the last armour-piercing round was the W Mark 1Z in 1945, and the last incendiary round was the B Mark 7 in 1942. Explosive bullets were not produced in the UK after 1933 due to the relatively small amount of explosive that could be contained in the bullet limiting their effectiveness, their role being successfully fulfilled by the use of Mark 6 and 7 incendiary bullets.

In 1935 the .303 O Mark 1 Observing round was introduced for use in machine guns. The bullet to this round was designed to break up with a puff of smoke on impact. The later Mark 6 and 7 incendiary rounds could also be used in this role if required.

 

[Soren]

Regarding the MV of the MK108, it varied from 505 m/s to 525 m/s depending on the round fired, while rate of fire was 650 rpm, which is pretty darn fast.

 

[kool kitty89]

Ok, but that wasn't brought up here, but one thing: didn't the German system for recording MV actually used the velocity at the muzzle, opposed to allied testig which was for some distance after. (I can't remember the specifics)

And 650 rpm is excellent for a weapon of that callibur (even if you take to low MV into account it's good) but: The WWII Fighter Gun Debate: Gun Tables

Some effort was made to increase the rate of fire, and a 850 rpm version was apparently perfected, although too late to be adopted.

 

[Soren]

The Germans measured the MV some distance from the barrel as-well KK, and it's still std. practice to do this.

Furthermore that site has got the MV for the 7.92x57mm round all wrong, the muzzle velocity was 890 m/s with the 10.5 gram projectile and 865 m/s with the 11.5 gram projectile.

 

[kool kitty89]

I noticed some of that too. (mostly for the German guns, also in the MG FF/M, MG 151/20, and Maybe MG 131)