replicating action movie results, by the book

[Varyon]

Shotguns in a cinematic campaign should do knockback - possibly double knockback, if not more. Assuming 640 lb, the terminator would have HP 17 for knockback purposes (as an Unliving object, it would actually have ST 34 or 35, and HP to match, but I think you use the HP of a Living object for purposes of knockback; at least, you should). That means a knockback threshold of 15. A close range blast from a shotgun is generally going to be 4d+4(0.25) pi++, for an average of 18. So if you have shotguns deal knockback like a crushing attack, that's 1 yard of knockback on a T800 (and just 2 yards on an HP 10 human), while if you have them deal double knockback (36, above), you're looking at 2 yards (4 yards on an HP 10 human).

In a campaign where firearms deal knockback, something firing 5.56 is generally unlikely to cause much, as it's infamous for firing a rather light bullet (indeed, its width isn't much more than a .22 LR - 0.223" - but it is markedly heavier and traveling well above the speed of a .22 LR). I could see cause for a setting switch where firearms cause knockback to have pi- do half knockback, pi do normal knockback, pi+ to +50% knockback, and pi++ do double knockback. Firearms that fling bullets that should be pi- but get upgraded to pi due to high velocity would be treated like pi- in such a setting. So, a .44 magnum firing hollowpoint rounds for 3d+2(0.5) pi++ would deal, on average, 25 damage for purposes of knockback (3 yards against an HP 10 human), while an M16 firing FMJ's for 5d pi (treated as pi- for knockback) would only deal, on average, 8.75 damage for purposes of knockback (just enough to knock an HP 10 human back 1 yard).

[johndallman]

Originally Posted by Pursuivant

I've come to the conclusion that TV and action movie fights just can't be properly modelled in GURPS. Fighters are almost always too close together. Their blows are always too slow. Their moves are often not just telegraphed, but mailed via certified mail with an RSVP on the envelope. Defenders ignore obvious counterattacks. Attackers never feint and seldom use set-ups.

And all of those things have a common reason - the need to let watchers follow the fight - that doesn't exist in a TTRPG. There seems no need to worry about them.

[Gold & Appel Inc]

Originally Posted by sir_pudding

This is the entire point of GURPS Action!.

Originally Posted by Icelander

But the shotgun was grabbed from a squad car and thus extremely unlikely to be loaded with slugs.

As far as I'm concerned, this was not physics, but aesthetics. Shotguns make big booms and should, therefore, in the kind of game where function follows coolness, cause big knockback.

GURPS has optional rules for such silliness. Check out Gun Fu.

Have I mentioned lately that I really appreciate you guys?

ETA: This is by no means limited to the quoted texts; I love this entire community.

[Polydamas]

Since this ten-year-old thread has come back to life ...

Hans-Christian V's blog Shooting Dice has writeups of many gunfights from films and TV, although he prefers less cinematic action https://shootingdiceblog.wordpress.com/

GURPS Gun-Fu and GURPS Action are definitely the books for cinematic gunfights!

[jacobmuller]

Originally Posted by Varyon

In a campaign where firearms deal knockback.

There's something there - how about they do half knockback* on failure to penetrate... And things that normally do knockback get double... And knockback partially negates the injury... Baseball bat hits Joe Average for 4pts - Joe staggers back a yard, 0 HP injury...
*Might need to be they still do 1/4 if they do penetrate.

[Pursuivant]

Originally Posted by johndallman

And all of those things have a common reason - the need to let watchers follow the fight - that doesn't exist in a TTRPG. There seems no need to worry about them.

Exactly. If you're trying to do a GURPS conversion you have to think in terms of "relative badassery" rather than exact combat sequences.

If you're trying to model TV action melee or unarmed combat shot for shot, however, I think my suggestions still apply.

For R-rated fare, you can have relatively realistic gunfights, as nicely modeled by the Shooting Dice blog and the High-Tech and Gun-Fu supplements.