Go read it, then come back.
Got it? Good.
That reminded me of something I’ve played with playing with in the past, which is making it harder and harder to actually reach the vitals with something before it gets dangerous.
Let’s call it a Vitals Threshold.
Further, let’s assume that it’s about 2 HP, or 1d/2, just to toss out a number.
That might be HP/5, or it might simply be something like the aforementioned 2HP x half the linear scale for your SM. SM+0 is 2yds, so it would simply be 2 HP. SM+4 is 5x that, or 10 HP. The first 10 HP would never get a damage multiplier, for things that aren’t wrapped around brains.
That’s still not that bad. You’re shooting the vitals of a SM+4 target at a net +1 to hit. At 5d, you’re averaging a 17 point damage roll, and with x3 for vitals and no real DR, you’re looking at 10 + 7×3 = 31 points of injury instead of 51. That’s a decent reduction, but it’s still 31 flipping points of injury.
I’m not sure that’s too wrong. The African Elephant clocks in at about 10,000 lbs (5,000 to 14,000), which is about SM+3.2 to about SM+4.5, I’d say, based on mass. And poachers kill those with a 7.62x51mm FAL with too-often frequency.
So maybe it’s still OK. A 7d weapon might do 3d basic injury getting through to the vitals, and then 4dx3 inside the important bits. About 15d injury (50-ish points). I think the other key bit for penetration’s sake is the bullet size modifier. I’d highly endorse taking a pi bullet and scaling it down by SM. So shoot a SM+4 target and your injury might get taken down by 4x.
That starts to look attractive. The SM4 giant would “only” take 2-3 HP from the inbound wound track, and about 3d (10 points) from the vitals wound, for 12-13 HP per shot to the vitals.
You can do it with a whole bunch of shots (and that’s how it’s often done on big creatures) to the vitals, but if you’re just unloading and hoping to get lucky your target will absorb a lot of shots. It also means using (say) a 9mm pistol won’t even reach the vitals on the average.
That’s leaving off the amount of DR that thick hide, fat, or actual armor might bring.