Armour vs Machine Guns ...

I've been looking at the data on some light tanks of the era and it got me thinking - what thickness of armour plate was proof against heavy machine guns in WW2 ?

 

That would of course depend on the machine gun, but around 10 mm would probably be a minimum for most 12,7 mm machine guns. Germany used 7,92 mm machine guns as heavy machine guns in infantry squadrons, which couldn't penetrate as much, but they did adapt some Luftwaffe aircraft machine guns for ground purpose late in the war. The 20 mm Flak 30/38 could of course also be employed against ground targets, being able of penetrating up to 20 mm.

 

What about the .50 cal. M2 round?

 

A 12.7mm round is the same as a .50cal

Unless there is a difference in the American rounds that would allow it to penetrate more?

 

The Americans used two types of ammunition for the M2 HMG, ball ammunition and AP ammunition. The latter was capable of penetrating about 30mm of armour at short ranges.

 

The typical maximum penetration (short range, vertical armour) of rifle/MG 7.6-8mm steel-cored AP bullets was about 10-12mm. Allowing for range, and the fact that the bullets would almost certainly strike at an angle, around 8mm should provide enough protection. Similarly, about double that should protect against .50 cal AP.

The Germans did have some tungsten-cored 7.9mm AP ammo at the start of the war, they used it in Pz I guns. This could penetrate a maximum of 18mm, so you'd need at least 12mm of armour to keep it out.

Tony Williams: Military gun and ammunition website and discussion forum

 

Thanks for the answers chaps.

As an progression of this point it might be interesting to compile a list of armoured vehicles that were vulnerable to machine guns as with the US halftrack that General Patton cited as something of a liability because of the false sense of security it gave to its passengers.

 

I'd probably say most halftracks and light tanks.