Resistance of armoured steel to armour piercing and reversed bullets

[centurion]

http://www.royalarmouries.org/assets-uploa...Miris_Steel.pdf This link connects to two photos from early 1916 the second showing the effect of reversed Mauser bullets and French armour piercing rounds on a specimen steel plate when fired at 30 metres. An interesting feature is the close grouping of the armour piercing rounds and the spread of the reversed bullet even at so close a range (one assumes that such a test would use a rifle on a fixed stand) which might indicate that using reversed bullets against a sniper's loophole at 100 yards firing from the shoulder is very likely to be hit and myth.

Unfortunately we can't see the back to see if there is any spalling but I wonder if the French AP rounds that seem to have part penetrated the plate would have had some effect on the reverse surface.

The Brodie shown may have stopped the round but I suspect that a wearer would have such a headache that he wouldn't be able to play his harp for ages!

[Old War Skule]

That's interesting. Equally interesting is the mention of a US Army AP round in 1916. Could it have been developed as foresight or by outside request?

I saw a WW II US M3 Stuart tank that had been hit with AP rounds from a machine gun. It looked as though the core only chewed up the armor without penetrating. I have no idea what the inside was like.

A chap wearing that Brodie, I believe, would've had a fractured skull and as said not been "right" for years.

[centurion]

In 1920 Dr Bashford Dean of Yale published "HELMETS AND BODY ARMOR IN MODERN WARFARE". This includes most trench or sniper shields used in WW1 and includes the results of tests carried out on them. The following extracts may be of interest.

German shield 1914

It was made of a silicon-nickel steel .23 inch thick and was proof to machine gun fire at about 100 yards, even when the bullets were reversed. It failed, however, with armor-piercing shells.

French Daigre shield

That the Daigre shield was of practical value there can be no question. Tests at close range showed that the German service bullet, even when

reversed, failed to penetrate it. On the other hand, it is not proof to armor-piercing bullets even at moderate range.

Belgian shield

The trench shield was manufactured for the Belgians by or through the firm of Rosenwasser Brothers of Brooklyn. This is of the same width but higher (24 x 31 inches) than the German shields mentioned. It is proof to service ammunition and to a reversed bullet at 50 yards. It is made of a chrome-nickel plate .29 inch in thickness, and is enclosed in a canvas jacket. It weighs about 60 pounds;

In general

Regarding the weight of steel for "trench shields," it is found that any good alloy steel to resist at 50 yards service ammunition, German, English or American,

should be at least .20 inch thick; this entails the weight of a pound for each 14 square inches of surface. To stop a German bullet reversed, the plate should be .30 inch thick, giving a weight of 12 square inches to the pound. To stop an armor-piercing bullet, a plate of the best alloy should be at least .40 inch thick or a pound for each 9 square inches of surface. (Since the foregoing was written, the results of governmental tests on new molybdenum-nickel plates have been received from Dr. G. W. Sargent of the Ordnance-Engineering. These show that a thickness of but .30 inch is necessary to stop service A. P. ammunition at 50 yards ; or .26 at 100 yards

[robert_sfl]

Does anyone have a ballistic chart to tell at which distance the 7.92x57mm IS reaches the mentioned 850ft/s? The muzzle velocity lies around 2,600 ft/s I think. The brodie was a bit thinner that 1 mm I believe.

Of course that article was placed by Miris Steel co. itself, so it would likeley have advertising character rather than beeing a neutral test. Nonetheless very interesting!

[centurion]

Bashford Dean cf states that the British made a particular study of the effects of AP of all types including reversed rounds. Unfortunately he gives no detail of the results of these efforts, however Stern does quote some results of firing tests against thin armour plate (about .30). From this it would seem that a reversed round had to be fired from closer than 10 yards to penetrate. How much closer he does not state.

[David B]

Notwithstanding the headache aspect I'd hazard a guess that without it the subject would have been KIA.

[centurion]

Notwithstanding the headache aspect I'd hazard a guess that without it the subject would have been KIA.

Hence my comment about him not being able to play his harp - think I'll give up on the humorous aside

[MikB]

Does anyone have a ballistic chart to tell at which distance the 7.92x57mm IS reaches the mentioned 850ft/s? The muzzle velocity lies around 2,600 ft/s I think. The brodie was a bit thinner that 1 mm I believe.

Of course that article was placed by Miris Steel co. itself, so it would likeley have advertising character rather than beeing a neutral test. Nonetheless very interesting!

Educated guess is between 1000 and 1200 yards. Pretty good going to hit a tin hat at that distance...

Regards,

MikB

[TonyE]

The .303 Mark VII drops to 840 fps at 1400 yards. so as the 7.92 kicks off somewhat faster I would think it would be down to 850 fps at around 1500 yards. That assumes a similar ballistic coefficient for both rounds which for the purposes of approximation is true.

Regards

TonyE

[MikB]

The .303 Mark VII drops to 840 fps at 1400 yards. so as the 7.92 kicks off somewhat faster I would think it would be down to 850 fps at around 1500 yards. That assumes a similar ballistic coefficient for both rounds which for the purposes of approximation is true.

Regards

TonyE

Ah, but it'll be lower for the 7,92, won't it - about 20 grains less and about the same cross-sectional area...

Regards,

MikB

[MikB]

...but I've just checked it on a ballistics program using the same coefficient (0.369) as Speer's 150 grain 8mm. Spitzer, and it runs out about 1360 yards, so I'll have to give TonyE that his is closer than mine...

(just )

Regards,

MikB

[Tom W.]

Hence my comment about him not being able to play his harp - think I'll give up on the humorous aside.

Actually, in Goldfinger when Pussy Galore asks Bond where Goldfinger is (after he got sucked out the window of the crashing jet), Bond says, "He's playing his golden harp." So you could say that the hypothetical wearer of that helmet would be much better at playing his harp after the shot than before.