'Shotguns have dkb/dbt' - where did that myth (?) come from?

[Anthony]

Incidentally, it's not unreasonable to say that a shotgun slug has twice the knockback of a rifle bullet with comparable damage; it's very likely true. It's just that neither weapon has meaningful levels of knockback.

[SimonAce]

Here is a police training video that covers everything you might want to know about shotgun ammuntion including the oddballs.

The only thing not covered was AP slugs vs body armor as I suspect that made the cops queasy

[LuciusSummers]

Fundamentally no gun causes significant levels of knock back.

Simple rule of conservation of momentum and energy.

Every force that a bullet has is given to it in the moment of firing. As momentum at that point must be conserved the amount of knock back a round has is equal to its recoil.

So unless you can see the firer flying backwards will smith style (from Men in Black) the gun is not going to have significant knock back. Of course this is still able to trip people if they do not have good footing same as if you try and fire a shot gun without properly bracing.

As for broken ribs etc. Concealable vest - good approximate for a modern bulletproof without plates etc. Is DR 12 against the average damage of a rifled slug for a shoty (either because they were firing them or as gurps models a close quarters blast from a buckshot) is 18. Thus 6 (12 considering the pi++ bit) points would go through a major wound at minimum and more than enough to cause a few broken ribs.

Else the 2 points of bruising it causes could also cause broken rib or two. Most hospitals would consider someone with a broken rib or two to be in the Good category of injury in the GURPS campaigns (page 421) which is someone with HP over 50% but less than 100%.

End of the day what the injury is specifically is flavor added by the GM. So id sat GURPS already supports what you have said.

[HuManBing]

SimonAce, that website has another test (test #3, the wall penetration test for shotgun ammunition loads) which includes this "unofficial" finding:

4. I "racked" the shotgun several times during the tests, and no bystanders lost control of their bowels.
Conclusion: Racking a shotgun will not make the bad guy faint.

:D

[Ragitsu]

Glitterboy, anyone?

[HuManBing]

According to that fascinating site, BoxOfTruth, shotguns can be superior to both pistols and rifles (both assault and full calibers)... but only in very specific circumstances.

Penetrating body armor and penetrating walls (this thread topic) - about the same as pistols:
Poorest: buckshot pellets. Minor: pistol rounds, shotgun slug. Major: assault rifles. (Bricks stopped all rounds after a few walls.) The AK-47's 7.62mm round caused the nastiest looking hole in the clay behind the body armor.

Good for: shooting straight into a padlock:
Poorest: Pistol, buckshot. Minor: rifle rounds (drilled straight through cleanly, locks generally still in working order). Major: shotgun slugs (broke the padlock in two).

Good for: shooting against "bulletproof glass" (actually 1.25 inch thick Polycast acrylic, a type of plastic, not glass):
Poor: Pistol, buckshot, assault rifle, and rifle rounds all failed to penetrate. Major: shotgun slugs (penetrated the glass easily).

So it seems shotgun slugs do have a limited range of specialized roles. But usefulness against body armor is not one of them.

[lwcamp]

Originally Posted by Anthony

For reference, knife-proof vests are generally normalized for a 40J impact, which is more than most people can actually deliver.

A quick check of my bookmarks shows this:
"Stabbing:
Underarm: up to 63 J
Overarm: up to 115 J
(These are maximum values. PSDP testing suggests that a stab resistant vest rated at 43 joules should be able to stop stabs from 96% of the male population. These standards assume typical commercial knife handles. A fighting handle with a well designed guard to prevent slipping might add another 5 J to the effective attack."
from http://willscommonplacebook.blogspot...vs-muscle.html
I haven't checked the references, use at your own risk.

Luke

[Biker Matt]

Originally Posted by Anthony

A well-delivered punch involves torso muscles, but the actual impact mass is much smaller. Essentially, a punch uses a mechanism very similar to a whip crack to transfer rotational energy generated in the hips and torso into hand velocity, but the mass which is actually relevant for knockback purposes is only the hand and for some types of strike the forearm.

I make use of two techniques, and call them Forearm Strike and Shoulder Bash (Incidentally, This is Mechanic-from-Reality here!). As near as I can determine, FS deals double Thrust damage for purposes of knockback, but half damage for purposes of HP loss (the attack deals 2d, with a 1/4 multiplier after determining knockback, averaging a bit under 2 listed damage, but 7 average knockback damage), and SB dealing x3 and 1/3 (3d rolled to average 10.5, and barely over 1 result damage). If you include the "knockback safety" rule (which I do: each hex of knockback = -1 damage, and knockback based on ST-3 rather than ST-2), FS usually deals 1 point of damage, and SB rarely deals any damage at all! If you treat Shotgun damage the same way, you may get that 1d+1 or +2 of regular damage, and some multiplier for knockback damage (averaging, say, 18-22 points for purposes of knockback, making your average person go back 2-3 yards with the single hit), which brings it MUCH more in-line with the other firearms listed in terms of effectiveness (and that much more realistic, too!)

remember, I'm estimating the rules based on what I KNOW I can do!

[combatmedic]

Originally Posted by HuManBing

SimonAce, that website has another test (test #3, the wall penetration test for shotgun ammunition loads) which includes this "unofficial" finding:



:D

Well, the baddie in question may have a rather different reaction if he's crawling through your window at 4 AM, instead of watching you shoot at a wall on a firing range.

[Biker Matt]

Originally Posted by Icelander

Opinions are like fundamental orifices. Everyone's got one.

That doesn't change the fact that a ball of roughly .33 caliber travelling at low pistol speeds will perform poorly against body armour. And adding eight more similar balls won't magically make any of them perform better (and the odds of them impacting at precisely the same spot are minimal).

A tactical vest that's proofed against 9mm will also protect against anything up to triple-ought buckshot. Depending on design, it may leave broken ribs or it may be difficult to even notice during an adrenaline-charged encounter. Needless to say, vests of the former design will have a poor reputation with actual operators and will usually not be issued to police or military.

sorry to say, but my roommate's a marine, and he's shot a 9mm into a plastic milk carton and had the bullet bounch off!