[headquarters]

slug :
dmg : 6 pen : 4-5-nil rng : 7 ( depending on barrel length)
* damage to shooter : dmg 1D6-4 location roll head / arms

buck :
dmg close rng : 11 pen :nil rng : 7 ( depending on barrel)

dmg medium rng : 1D12 (treat as 2x10 brst total of 14D6 to hit)
* damage to shooter : dmg 1D6-4 location roll head / arms

as you can see I have determined that shooting such a gun is hazardous and may result in damage - enough to knock you out cold depending on CON score.Slight damage is likely but not guaranteed.

other stats may be tweaked by using different loads and different lead configuration .Perhaps a higher damage could be given .

Gen Pain - with a minimum damage of 11 hp for the "Buck" shot -there is your guaranteed knock down in one shot gun .
I still say a dbbl 12 gage sawed off is more bang for buck in terms of practical applications in the T2K world.

all off the top of my head guys.