How to Stat Ghost in the Shell Style Hypervelocity Ammunition

[Varyon]

Originally Posted by GURPS Fox

That requires sending such a round at tremendous velocities (well above 1km/s minimum, though some calcs indicate that this can go as high as 11km/s, everyone agrees that's just plain insane as no conventional propellant can achieve such velocities).

That's pretty hefty, no matter what you say about it.

As a note here, a 9mm bullet typically has a velocity around 350 m/s, and GURPS firearm damage typically scales linearly with velocity. So, determining what velocity would be required for that amount of recoil force will give you your damage. 1050 m/s (just above that 1 km/s minimum) would be 3x damage (as 9mm typically does 2d+2, that's 8d-1); 10,850 m/s (just below that 11 km/s maximum) would instead be 31x damage (80d-1).

Of course, I'll note that, if you're basing the "recoil pushback" off the garbage truck scene from the 1995 movie, I'm not certain that guy was a full body cyborg. He obviously had a neural interface (couldn't have had his brained hacked otherwise), and his jumps imply some leg enhancements, but I don't recall any indicators that he was extremely heavy (Motoko breaks off pieces of a building while scaling it in the scene, and severely dents the roof when she lands on it; he rocks some small boats when he jumps on them, but then a human of ordinary weight would similarly rock them when jumping off and landing from a few meters' height). Changing him to be of comparable weight (or perhaps a bit heavier) than a normal human will tone down the amount of power those bullets would need.

All that said, it's also important to keep in mind that GitS is rather cinematic; while I don't recall if it happens in the movie, it seems to be the kind of setting where someone would get thrown back a few yards from a point-blank shotgun blast. So you could interpret the recoil pushback to just be indicative of more recoil than normal, not that it would literally have enough recoil force to push the character back like that.