Where do all those extra bullets go?

In my comments on Rapid Fire and Shotguns in GURPS Fourth Edition, Roger Bay-West’s GURPS 101 post, I noted that he didn’t touch on hit location.

This is a bit of an oddity in the GURPS rules if you think about it too much. If I fire a birdshot load with (say) #6 steel shot at a target, technically I can aim at the vitals. Let’s say my foe is 30 yards away, and I’m pretty good, with Guns (Shotgun)-15. 30 yards is -7, and I aim for a bit, giving me +3 for Acc and another +1 for taking my time. Toss in +1 more for AoA(Determined). That’s a net of -5 including -3 for the vitals, but then we figure the RoF bonus for 317 pellets. That’s another +8 to hit, netting me a skill roll of Guns-18.
Shotguns have Rcl 1, so an average roll will hit with 9 pellets. Technically, all in the vitals.

Now, I’ve got a house rule around here somewhere tamping that down, because the 2.8mm, 1.4 grain pellets just aren’t going to wound well. In my rules, instead of 317 pellets, each of which should do something like 1d-5 {0.1} damage, I aggregate them into clusters of pellets that each can do a real pi- {a 0.5 multiplier} and that becomes RoF 57 instead of 317, and does 1d-5 pi-. Basically, you group them into about 5.5 pellets per effective hit. So instead of Shotgun-18, hitting 9 times, you’d have Shotgun-16, hitting 7 times, which really represents about 39-40 pellets that strike home.

But I digress. The point is . . . if I managed to put nine pellets on target (or 40, it almost doesn’t matter) . . . what happened to the other wholes-a-bunches of pellets? They miraculously missed the entire guy?
I mean, if the pattern is roughly circular, it’ll be about 30″ in diameter at 30 yards, more or less. If it’s a pretty good pattern, that’s about 2-3 square inches per pellet. Since some pellets hit the vitals, which is pretty well dead center on a human target, at worst you’re probably looking at slicing a chord of a circle from the edge to about a quarter way in.
Just looking and playing with the drawing, the body occupies about 1/4 of that circle, which is supposed to represent about 30″ in diameter. Again, with an even spread, you’re looking at about 80 pellets hitting just spreading it out. 
So with a shot like this, something crazy sort of has to happen – though less crazy with my house rules, which would give about half of the pellets hitting the vitals (though that would also be with the circle more centered, I think, since the roll was made by 6).
So, what about the rest of the shots?
All Suppression, All The Time

In short, if your weapon is capable of suppression fire (RoF 5+) then you get a chance to do some effective suppression fire. Take all the shots that miss, and roll again, this time at 8+ the RoF bonus (Guns-16 or Guns-14, depending on RAW or my house rule). Typically, that will give another 7 or 5 hits, representing another 7 or 28 pellets, respectively. These are each a random location.
Total hits is thus the original hits to the targeted location, and the bonus random hits.
  • Using RAW: 9 of 317 pellets hit the vitals, another 7 hit random locations, and 299 continue onward.
  • Using my house rule: 7 of 57 pellet clusters (representing 39 real pellets) hit the vitals, and another 5 pellet clusters (representing 28 more real pellets) hit random locations. Total 67 real pellets hit, or 12 of 57 pellet clusters, thus threatening friends and neighbors with 45 clusters.
Actually, this makes my house rule look pretty good, since the target number of 80 pellets is about right.
All shots that don’t hit by targeting or by chance go on to menace anyone in the firing path of the bullets (at least, in my games).
Note that while the first case is a bit artificially inflated, the typical 3600 rounds per minute Gatling gun is well represented by the second case without inflating for pellet clusters. You fire roughly 60 shots downrange, but at Rcl 2 rather than 1. Acc 5, though. Braced, Aimed, etc is probably something like Gunner-20, for 11 hits to the targeted location, and then another 2-3 hits to random locations. So about a total of just shy of 25% hit rate, of course most of those are to the target, rather than some smaller number.
Parting Shot
I like the idea of resolving shots that don’t hit the target directly as suppression fire first on the target itself (thus achieving some number of random hits), then with the threat of hitting anyone crossing the firing path.
One thing that would be interesting is to resolve these attacks the other way. When using targeted autofire like that, the smaller hit number will always be that at the targeted location, while the larger is resolved for random shots. That would make opening up at a person’s vitals with a ginormous machinegun more prone to have a smaller number of shots hit the vitals, a larger number hit randomly, and a still larger number scatter across the landscape.
I’ll have to test this more.

One thought on “Where do all those extra bullets go?

  1. Post topic suggestion: using LMGs in game, including with ambush tactics and suppressing fire. My take on this would be similar to your sub-heading up there: All Suppression, All the Time, but I'm not sure how truly effective that would be at range. Good stuff, as always.

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