Landships II

Paul Bonnett · Hero

Small arms strikes on armour.

Pzkpfw-e · Commander in Chief

Too small to bother with.

Tanker · Field Marshal

Paul,

Look at these photos from Groupe AS 3, in Gouy-les-Groseillers, after fights from Bois Sénécat.
https://argonnaute.parisnanterre.fr/Blog-des-collections/p42/Les-albums-Valois-50-000-photographies-de-la-Premiere-Guerre-mondiale-accessibles-en-ligne
Cote: VAL 275/191 - VAL 275/193 - VAL 275/194 - VAL 275/196
Date: 1918-04-01/1918-04-30
Contexte : Fonds des albums Valois - Département de l'Oise - Volume 27 > Gouy-les-Groseillers

These 4 photos, was French miltary photos from Ecpa-D Fort d'Ivry n° SPA 121 R4410 - SPA 121 R4414 - SPA 121 R4418 - SPA 121 R4419.

These photos are not in the best quality on the Fonds Valois, but very good in Fort d'Ivry.
Around each hole from 7,92K, a white round lip of steel.

On an other photo from this serie, a man put a finger inside 13 mm hole. The first plate was perforated, but not the second. This fight was the first, against 13 mm rifle, for the french tanks.

Bonne journée - Michel

Peter Smith · Captain

That's a difficult one. Armour plate of the day was actually quite brittle, so penetrating strikes will most likely leave jagged holes rather than neat round ones. Ball rounds - those with lead cores - would generally not penetrate but would deform against the hardened surface. That would take the paint off and probably leave a lead/copper smear. If the strike was on a plate join the bullet might end up jammed in the join.

The MkII at Bovington still has evidence of various projectile strikes, although the vehicle has been repainted more than once since they were inflicted. However, that is a mild steel tank so the damage patterns will not be the same as with armour plate.

CharlieC · Legend

The A7V #506 Mephisto sat on or close to the front line from April to July 1918 and is peppered with small arms strikes especially on the left side.

Aside from a couple of dents from larger projectiles (possibly 37mm) you have to get close to the tank to notice the strike marks. None of the

small arms strikes on Mephisto are penetrating - which is also a finding noted from firing tests with 8mm rounds on the armour plate from #542 Elfriede.

My understanding of armour plate in WW1 was that it was based on the principles of naval armour - a hardened outer layer which shattered a projectile

on impact and the bulk of the plate was more malleable and deformed to absorb the impact energy.

Regards,

Charlie

Peter Smith · Captain

Charlie, your understanding is correct. Most commonly now called face hardening, although in the past it has gone under other names such as Krupp and Vickers Cemented Armour and Harvey Armour.

Face hardening means and does what it says: one side of a plate or casting is hardened by long heating at high temperature in contact with a carbon-bearing material such as charcoal. The whole plate or piece is heated but only 1 side has the carboniferous substance applied. This is called the Striking Face. The back face remains tough and elastic. But in very thin plates as used in WW1 the whole plate could become brittle. It worked better on thicker plates such as used on warships and later on tanks.

Cemented Armour also means what it says, but no-one understands it, and it has nothing to do with concrete!! Cementing refers to the absorption of carbon into the striking face, which is fundamental to the hardening process. The idea has been around since about the middle of the 19th century. German armour plate was, for the same thickness, generally better than British (Britain was still buying Austrian-made plate for tanks up until the Anschluss in 1938). And during WW1 we needed a lot of it quickly, so much so that its production and distribution for tank production was placed under centralised control. Production may have been rushed.

So yes, a small arms ball round strike on WW1-vintage face-hardened plate will most likely not cause any noticeable physical damage in model scale apart from paintwork. Copper and lead are softer than hardened steel. Shell fragments could cause dents or (jagged) penetrations depending on shell size and detonation distance. Steel shrapnel balls might cause dinks or possibly even penetrate: lead ones would just take the paint off again. "K" AP rounds would make slightly indented round holes, potentially a jagged hole with the larger rounds from the T-Gewehr. Thinking of Mephisto, Allied forces did not have any AP SAA - why would they - so the damage observed would all be standard copper and lead ball rounds.

A post above mentions a silvery lip around K round penetrations. K rounds and T-Gewehr rounds were steel-cored, not solid steel. The front 3/4 was copper-jacketed but the rear 1/4 recessed inside the cartridge case was bare steel. So the silvery lip is almost certainly the melted copper jacket deposited around the hole as the steel core penetrated. Some parts of FTs were relatively thick castings, which would have behaved differently to strikes than plate.