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Old 05-09-2017, 02:53 AM   #35
Join Date: Jan 2010
Location: Brighton
Default Re: High Amounts of non penetrating damage. Bullets VS Plate Carriers

Originally Posted by DeathDaisy View Post
Aha, I'll check it out, sounds like a reasonable rule.
I find it works well (but IMO needs the bleeding rules as well)

Originally Posted by DeathDaisy View Post
Fair enough, I'm far, far from an expert and just went with gameablity, so I'll concede :) Might still try it in my own games tho, see how it works out, maybe cap the damage at even less, just a few points or so.
No worries, neither am I, give it a go and see how it works!

Originally Posted by Varyon View Post
Bullets usually don't have that kind of momentum. A bullet fired from a tank's main gun, or even "just" a mounted anti-materiel rifle, could very well have such. Like I said, it's not entirely unrealistic, just extremely unlikely, as the sort of impact pressures that would have to be involved will usually punch through the armor.

Look at the kind of damage you need for that knockback - my example called for a DR 60/5 armor before the effect came into play. You don't get this kind of performance with weapons that can be hip-fired. As for the action-reaction effect, I don't think there's a single weapon where MinST is low enough for an average hit* to knock the wielder back, and considering the shooter is going to be better braced for impact than the target, things should work out alright here. Yes, this does mean an M14 will, on an average-but-nonpenetrating hit (meaning he'd need to be wearing armor that would put Ned Kelly's to shame), knock an ST 10 character back one yard. Part of that is GURPS' unrealistic (but easy to use) knockback rules, of course, but for the modest cinematics GURPS defaults to, it doesn't seem like a bad rule. The lesser reduction for pi++ means you only need around 4d+2 to manage that knockback, which can be a bit more problematic, but not game-breakingly so.

*Higher than average damage with a firearm doesn't mean a more powerful bullet, it means hitting a higher-value target, impacting at a better angle, or similar.

Ah OK right, sorry I thought you we're referring to the proposed house rule, yeah, tanks guns etc lots of momentum! (at the personal level)

EDIT: sorry just looking again at the second second section of this, I'm no sure what you mean when linking MinST to Knock back? And I'm not sure a 10g bullet travelling 830m/s will knock back a human sized target (in lots of armour) a yard if it collides but doesn't penetrate. But then knock back in GURPS is a lot of different things.

Originally Posted by Anthony View Post
It's actually just a conversion of RL to RL. Basically, the NIJ standards for armor specify a list of attacks that must fail to penetrate, and also specify a maximum amount of backspace deformation by listed attacks. The maximum appears to be 44mm, which is actually quite a bit; enough that a point of non-penetrating damage seems reasonable (this is actually a sort of reasonable general rule -- since the backface standards are consistent, just assume any attack that barely fails to penetrate does 1 point of blunt trauma, and ignore the existing rules for nonrigid armor).

However, level IV armor is rated to stop 7.62mm AP, and while there are no specific standards for resistance to weaker threats other than they also have to not get through, there's not really a plausible design for plates that suffers the same deformation against 5.56mm as it would against 7.62.
I think I'd hesitate before I'd equate 44mm of back deformation to 1pt of damage, simply because I don't think there's such a RL to GURPS conversion rate.

What's 1pt of damage or 2 points etc is subject to an awful lot of variable beyond just how far back did the plate push/bulge

However that said as per my post 18 I don't actually think the best way to look at this is have 1 or 2 (or whatever) damage applied uniformly, as blunt trauma usually is. But rather to call it Cr and allow it the varied effects on location as per MA injury rules.

Last edited by Tomsdad; 05-09-2017 at 05:20 AM.
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