Armor Penetration - 20mm vs. .50 cal.

[DAVIDICUS]

Specifically, the 20mm Hispano II and the .50 BMG.

1) What is the armor penetration of each with armor piercing ammunition?

I believe the .50 BMG has a higher sectional density and roughly equal velocity at the muzzle. In adition, it's ballistic coefficient allows it to retain velocity better.

[DAVIDICUS]

I have read that a .50 BMG AP round can penetrate .9" of face hardened armor plate at 200 meters and .5" of face hardened armor plate at 600 meters.

I can't seem to find anything on the 20mm.

[CharlesBronson]

Some old documents about this issue.

.303, .50 and 20 mm Hispano included.

LOL - was just about to post those. If I hadn't gone in and cut them down to save space, I'd have posted um first!

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Lunatic

[DAVIDICUS]

Thanks. I'm always learning something new on this forum.

[the lancaster kicks ass]

wow that's great info, it's amazing to see how, at 0 degrees the difference between 20mm and .50cal is 7mm armour penitration, but by the time you get to a 40 degree angle the difference in armour penitration is 11mm!!!

[DAVIDICUS]

Surprised me too.

I thought the .50 would have greater penetration due to its higher sectional density. (At least head on.)

[the lancaster kicks ass]

well it's never gonne beat a 20mm..............

Originally Posted by DAVIDICUS

Surprised me too.

I thought the .50 would have greater penetration due to its higher sectional density. (At least head on.)

Actually, if you think about it, it does. It penetrates 20mm vs. 27mm for the 20mm AP, but only has about 40% of the mass of the 20mm. "Head on", sectional density helps as the energy is focused on a smaller area, but once the angle starts diverging from perpendicular, the total mass becomes more relevant.

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Lunatic

[DAVIDICUS]

I am trying to figure out whether eight .50 cal.'s would have been as effective as four 20mm's for ground attack against moderately armored vehicles and ground positions.

I assumed they would have been but now I don't think so.

I think the answer is clearly yes. The area of coverage was higher, and the number of rounds carried was higher, typicaly 4 times as much. The .50's could easily destroy most half tracks.

It should be noted however that the Japanese specifically created many of their bunkers and pill boxes to be resistant to .50 fire, and against such targets 20mm were much more effective. However, the Germans tended to reinforce most of their positions to be tough enough to withstand either weapon.

Against most ground targets, the .50's were sufficient. Eight .50's with a total of 2400-3200 rounds had many advantages, and a few disadvantages, over four 20mm with 500-600 rounds.

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Lunatic

[the lancaster kicks ass]

but when it comes down to it there are targets that 8x.50cal can't take out that the 4x20mm can, that's when you wish you had the 20mm............

Originally Posted by the lancaster kicks ass

but when it comes down to it there are targets that 8x.50cal can't take out that the 4x20mm can, that's when you wish you had the 20mm............

Yes but they are relatively few. Most targets that can be taken out with 4 x 20mm can be taken out with 8 x .50's, though in some cases it will take more time on target to do it.


On the other hand, most targets can be taken out with 8 x .50's and the 20mm are just overkill. The reduced duration of fire means more sorties to achieve the same results. More sorties means lower odds of survival.

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Lunatic

[Soren]

As soon as any significant slant is applied to the target-armor, the .50 cal quickly looses its advantage !

Originally Posted by Soren

As soon as any significant slant is applied to the target-armor, the .50 cal quickly looses its advantage !

Most ground targets had less than 6mm of armor. Against that much armor the .50 is effective up to pretty severe angles. Also, most "armor" on most ground targets was not face-hardened plate, and the .50 cuts through softer steel pretty well even at high angles.

Finally, while it is true that there are plates that a .50 will not penetrate that a 20mm will, very multiple .50 hits will penetrate that same plate. The beaten zone of the .50 BMG was much tighter than that of the Hispano 20mm, and with more guns firing, the chances of scoring multiple hits within a one foot radius were pretty good.

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Lunatic