[ATE/HT] Blackpowder birdshot damage

[mlangsdorf]

So one of the assumptions for my ATE game is that manual action shotguns, often loaded with black powder loads, are a common and desirable weapon. Basically, something like a LeFever Nitro Special (Pulp Guns 1 p 25).

I'm trying to figure out the damage for a 12G 2.75" shell loaded with black powder and firing #4 birdshot for an encounter where a bunch of hunters suddenly find themselves in a bad situation.

Here's what I know:
* 12G 2.75" smokeless powder slugs do 5d damage
* 1 1/8 oz shells have about 150 pellets of #4 leadshot
* From High Tech p 172, that's NP =150 and NS = 0.082
* Birdshot does pi- (0.5) damage

Based on the damage from the Winchester 1887 in 12G, I don't think that using black powder reduces the slug damage from 12G shotguns, but I'm not sure about that.

Assuming that black powder slug damage is 5d (or 17.5 on average), the multiple projectile rules give the average damage as 1.5 or 1d-2. So these shotguns should be doing 1d-2 pi- (0.5) with RoF 2x150. Does that look correct?