[Pyramid 3/52] LT Armor Design: Mail vs Pi (Guns)

[Fred Brackin]

Originally Posted by Joseph Paul

Fantasy guns based on haquebuts and arquebuses are throwing up to 18-19 mm ball. So you might want to check if something that large is still piercing at the velocity it is going.

It's P++ at any gunpowder velocity. There may even be soemthing somewhere about lead sling bullets being P rather than Cr like stones.

[Anthony]

Originally Posted by Sorenant

As far as I know, bulletproof plates involves plackarts which acts like spaced armor and the curvature aided in deflecting the bullet.

Most bulletproof steel plates are fairly ordinary hardened steel. They're just rather heavy (level III equivalent is about 10 lb/sf)

[Sorenant]

Originally Posted by Joseph Paul

Fantasy guns based on haquebuts and arquebuses are throwing up to 18-19 mm ball. So you might want to check if something that large is still piercing at the velocity it is going.

I was thinking about more mordern guns like 9mm and 5.56mm.
I think those huge lead balls would shatter when impacting a hard enough armor (including mail).

Originally Posted by DanHoward

GURPS has separate blunt trauma rules for that.

So a theoretical mail made of strong metal can actually stop a bullet, with the only cons compared to a plate being the blunt trauma from its flexibility (about 1 extra injury for a 5d damage)? I must say I didn't expect that, I thought it would just break the ring and go right through the armor.

Originally Posted by Anthony

Most bulletproof steel plates are fairly ordinary hardened steel. They're just rather heavy (level III equivalent is about 10 lb/sf)

70lbs to cover torso? You'd need to be Captain America to wear that.
Ultra Strength Steel is quite forgiving then, it weights about 45 lbs for a torso piece.

[Anthony]

Originally Posted by Sorenant

70lbs to cover torso? You'd need to be Captain America to wear that.

Realistic trauma plates (two of which GURPS claims cover 'torso') are 0.6 to 0.8 square feet each.

[chandley]

The hard-to-substantiate word on bullet-proofed mail armor is it can be done, but if it is penetrated, little bits of shattered mail rings stuck in the wound are pure hell to find and remove. Even with modern x-ray and metal detectors. Steel plate deforms but tends not to shatter when penetrated.

Also, as mentioned, easier for modern tech to make large plates than to link up lots of little rings.

[Rupert]

Originally Posted by Sorenant

I think those huge lead balls would shatter when impacting a hard enough armor (including mail).

Lead balls like those don't shatter - they flow and deform.

So a theoretical mail made of strong metal can actually stop a bullet, with the only cons compared to a plate being the blunt trauma from its flexibility (about 1 extra injury for a 5d damage)? I must say I didn't expect that, I thought it would just break the ring and go right through the armor.

About 1 point of blunt trauma per 3d of damage, actually.

[Polydamas]

Originally Posted by Dustin

Even very ordinary mail doesn't have holes large enough for most bullets to pass cleanly through. They will have to break some links, just like a blade would.

Here's some mail with a ruler for scale
https://i.ebayimg.com/images/g/5vkAA...WEu/s-l400.jpg

So yes, for a magical material that's more than twice as strong as TL7 steel, why not DR 18?

And we don't have any kind of theoretical model for how mail works against bullets. What we know about low-tech armour is a handful of kitchen-counter tests supplemented with very rough-and-ready, spherical-cow physics principles. And ballisticians will tell you that you can run the models all you like but at the end you need to shoot a projectile at a target and see how closely it fits.

Mail was used to stop shell fragments and splashes of loose lead in WW I (when lead bullets hit the riveted skin of tanks, they had a habit of sending tiny through the cracks which blinded people).

[Fred Brackin]

Originally Posted by Rupert

Lead balls like those don't shatter - they flow and deform.

Cast lead bulets as used in the Old West can shatter when hitting hard steel. I've seen it in Mythbusters slow motion. Though that was plates and not mail.

Modern HP pistol bullets can shatter too with FMJ ones deforming catastrophically. It was only Total Metal Jacket pistol bullets that bounced in one piece with only some deformation. Updated to that "Iron Man" 3D printed titanium chest plate and even FMJ pistol bullets shattered.

Since most people don't have ultra slo-mo of the times they've had some bullet almost hit them after a ricochet situation it's possible that it was just the biggest piece that almost got them.

[Flyndaran]

Would it really matter whether they shatter into pieces or flow into pieces as any such pieces can still be lethal?

[Rupert]

Originally Posted by Fred Brackin

Cast lead bulets as used in the Old West can shatter when hitting hard steel. I've seen it in Mythbusters slow motion. Though that was plates and not mail.

Interesting. All the muzzle-loader ball, minnie bullets, and shotgun slugs I've ever fired into steel plates have deformed. Some of them have had small pieces torn off ('shattered' is the wrong word - they deformed and tore), but they never showed signs of shattering. Some of the .45" balls from a modern Hawken-style rifle, driven by maximum recommended black-powder loads were deforming 1/4" steel plates enough that several hits in the same place would go through, and they were smearing or 'splashing', but the remnants still could be seen to have flowed rather than shattering.

It's possible Myth Busters were using a harder alloy, perhaps?

Since most people don't have ultra slo-mo of the times they've had some bullet almost hit them after a ricochet situation it's possible that it was just the biggest piece that almost got them.

Ricochets deform but don't come apart in many cases - they'd not travel as far if they were in bits.
OTOH they are also usually hitting at a very steep angle, rather than slamming into something nearly square on.