Landships II

James H · Legend

TV Documentary on Unearthed Tank.

philthydirtyanimal · Commander in Chief

Looking at the clip you link to, I realised I have seen this episode. Its fairly good (not excellent, but fairly good!).

There is a model maker showing off his remote controlled 1/16 Mark IV (I think it was 1/16). They talk to the chap in charge of the surviving Mark V* in the Patton Museum.

And they test some armour plate of the same thickness that a Mark IV would have had. They discover that reversing�an ordinary rifle�bullet in its casing would give it the capability to penetrate a tank's armour.

Brotzie · Corporal

philthydirtyanimal wrote:

And they test some armour plate of the same thickness that a Mark IV would have had ... reversing�an ordinary rifle�bullet in its casing would give it the capability to penetrate a tank's armour.

You mean 'blunt' end first? What sort of range would that have? I'd have thought that the drag would make that a pretty close-range option, and also that it would be quite unstable (rifling notwithstanding). Intuitively, it would be no more than a 'barn door at ten paces' option...

The adopted solution of the trusty fifty-cal has proven more enduring - the 'original' M2 and�later M3 (higher cyclic rate aviation variant; now used on trucks in Afghanistan etc. - only problem is it shakes apart every couple of thousand rounds and has to be rebuilt).

�

philthydirtyanimal · Commander in Chief

Yes, just so, 'blunt end first'. I can't tell you where I heard the rumour or myth, that if the bullet is reversed in its casing it has more penetration, but evidently the makers of this TV programme had also heard the myth. They test the theory, and it proves to be true. I don't understand the ballistics or aerodynamics (its all just a load of parabolics to me!), but perhaps it didn't much change the 'effective range' of the German rifles, or perhaps it just didn't matter at 'battlefield range'. I think it is something to do with the 'squashyness' of the projectile; but whatever, the show has this interesting sequence in it.

Gwyn Evans · Legend

I didn't get to see the documentary. How were they able to identify it as F6 Feu d'Artifice? They just seem from the clip to be picking tiny bits of metal up. Even if they had the location right, wasn't F6 the Mark IV Male destroyed with Grasshopper II? How could they tell one bit of metal from another?

Gwyn

James H · Legend

I haven't seen it either, but I'll try to find some more info.

I think we might have discussed this before, but what is the story behind the circular opening in the front of the tank in the clip?

BTW: the reversed bullet. I've read that so often that I've always taken it for granted, although I have occasionally had some misgivings about the idea. It seems obvious that it would tumble in flight - very nasty for a human being, but surely not effective against armour plate. There are lots of references to it, but, of course,�there's always the possibilty that they are�cloned from an original.

The first thought that springs to mind is why it should have occurred to anyone to do it in the first place. It is much discussed here: http://1914-1918.invisionzone.com/forums/index.php?showtopic=21884&hl=reversed

In the UK we are somewhat limited in our ability to put firearms to the test, but our American friends have rather more latitude in that respect: http://www.theboxotruth.com/docs/bot32_4.htm

I have to say that the evidence�does not seem to be entirely conclusive.

Ironsides · Legend

Hi James Ive have also read numerous times of such bullets being used, as�I recall though it was not�specifically for armour piercing but to inflict maximum damage on the enemy by digruntled soldiers and was a widespread practice by�all nationalitys......�

What interested me most though was the mention of "Case Hardened Mild Steel Armour" I would think that this would hardly be effective against a normal bullet, battled damage to tanks suggests to me that something rather harder and more brittle was used, if any one can enlighten me it would be most appreciated

Cheers confuse

Brotzie · Corporal

I can see that a reversed bullet would be more forgiving in terms of dumping its energy onto a hard target than the normal business end of a round - see the recovered bullets in the Box o' Truth item linked above. The 'pointy' end would be more likely to ricochet and/or shatter when impacting armour plate, losing a lot of its kinetic energy in the process.

I imagine the consequences of getting a good 'mushroom' on impact would be to cause spalling on the inside face of the armour and, if there were enough residual energy, this could cause the round to breach the now-thinned armour; the breaching mechanism seems more likely to be Monroe effect rather than sheer brute force - if the bullet's musrooming then its pressure exerted per unit area of the armour must be reducing and so therefore must the probability of causing the armour to fail. Seems like an early, kinetic analogue of modern HESH round ballistics.

But I'm still with Nigel's point of view�in the Great War Forum discussion linked above, too. The aerodynamics of a reversed round must be pretty dire. Elmer Keith is a very reliable witness, so if he says there's no appreciable loss of accuracy out to a couple of hundred yards I'm inclined to believe that - but I'd equally put money on accuracy dropping to near-zero after that point. And he's only attesting to accuracy, not residual energy - a blunt, inherently astable projectile of that type would be shedding energy prodigiously just to get through the air.

So to summarise: reversed bullets would a been an expedient, limited-utility stopgap measure till something better came along - which didn't take long.

Rectalgia · Legend

I was most interested in the reversed projectile demonstration of the Codename Tank episode. Some thoughts and observations, for what they're worth, from someone who has actually perforated steel plate with rifle fire (but not with reversed projectiles, I hasten to add).

It is part of Australian shooting lore that one can penetrate the quarter inch side armour of a Ferret scout car all day long with a .243 Winchester at 50 yards (whereas a 7.62 NATO or .308 Winchester, having essentially the same powder capacity - and considerably greater kinetic energy - will merely 'dent' it). One of the shooting magazines published photos, many years ago. In a word, the answer seems to be velocity, the projectile is conjectured to 'melt' its way through steel and it probably doesn't much matter whether it is armour plate or mild steel, the result will be much the same.

Having neither a .243 nor a handy Ferret to deface I cannot absolutely vouch for that but I have punched holes with the greatest of ease through the discarded steel 'tyre' of an ancient Minneapolis-Moline tractor using a .22-250 (even higher velocity), firing standard lead cored hollow-point projectiles. The thickness of steel was at least 6 mm (I had in mind the assertions about the Ferret).

The entrance and exit sides of the penetrating holes both showed a raised crater rim - in the case of the entrance site that would seem to be a 'splash' effect, attesting to the fluid state of the steel on impact. If I recall correctly, the demonstration at the British army establishment in Codename Tank showed exactly the same sort of penetrating hole. Perhaps a contrary indication of the 'burn through' theory is that the holes are of more or less constant diameter all the way through (with burn-through one would intuitively expect some 'coning' of the hole). Consistent diameter seems more in keeping with the 'wad punch' model of penetration - but my .22-250 projectiles were the right way around, pointy end first. I just don't have an explanation for that.

How can reversing the projectile increase velocity? The powder/propellant charge was unaltered in the army demonstration if I recall correctly. To my mind, the main suspect would be the forcing of the blunt end of the projectile into the rifling on loading the round. This will increase chamber pressure significantly. Usually there will be a short 'lead' in front of the projectile (the throat of the chamber) before it contacts the lands of the rifling on firing and that reduces the pressure pulse from standard propellants, as is well known to ammunition 'handloaders'. The American experiments (referenced by another poster) avoided that (seating the reversed projectile well down in the case, knowing full well the effect on chamber pressure otherwise) but they seemed to be more concerned with accuracy and deformation questions, not with steel plate penetration.

The lack of 'streamlining' of the reversed projectile will have little measurable effect in the first 50 metres or so of a high velocity small arms projectile's travel in my estimation. If I recall correctly, Colonel Mayevski showed well over a hundred years ago that drag is non-linear and it is 'critical' at around the speed of sound - it is always going to be a huge factor and it is always going to increase as velocity increases - but the 'shape' of a projectile with a muzzle velocity of two to three times the speed of sound is not going to increase drag sufficiently for relative retardation to be easily measurable in the first 50 milliseconds or so of flight. If it starts out faster it is still going to be faster for some appreciable distance.

Much of the conjecture could have been set aside if only the army had used a basic (and cheap) chronograph in their demonstration. I am (reasonably) sure it would show a substantially increased muzzle velocity with the reversed round - though examination of the primer would be another indication (of increased pressure, implying increased velocity), not to mention noticeably stiffer extraction of the spent cartridge.

{sigh} there was a time when I had all the materials necessary to resolve all of this, including a 7.92x57JS ex-military rifle (the chamber tolerances are significant, I think, sporting rifles may be different) and a case of ex-Israeli 'pointed spitzer' ball ammunition. Well, I didn't have the chronograph - they used to be expensive back then. But, for what it's worth, my conjecture is all I can now offer.

Ironsides · Legend

�

Stern quotes the following from "The Log Book of A Pioneer"..

Notes as to Steel Plate obtained from Experiments Made
Nickel-Steel Plate
12 mm. thickness is proof against a concentrated fire of reversed Mauser bullets at 10 yards range, normal impact.
10 mm. thickness is proof against single shots of reversed Mauser bullets at 10 yards range normal impact.
8 mm. thickness is proof against Mauser bullets at 10 yards range, normaj impact.
High Tensile Steel Plate
6�mm. thickness will give protection against bombs up to 1 lb. weight detonated not closer than 6 inches from the plate.
N.B.It is proposed to cause the detonation of bombs
away from the top of the Tank by an outer skin of
expanded metal, which is not on the sample machine
shown.

Cheers wink