"Mary Shafer" wrote...

Not on my airplane, I hope. Nice tidy little bullets are one thing,
but a handful of shot is another entirely. Pressurization systems are
good, but there is a limit.

As in most things, "it depends"...

If you are thinking about a 10 or 12 gauge shotgun loaded with #4 buck or larger
in normal loads, you are probably right (though I haven't done or seen any
analysis). With "bird shot" (#7 or 8 lead), though, the trade-off would be the
close-range "column of shot" effect vs lesser penetration. Even with a cylinder
bore in a 18 1/2" or sawed-off (highly illegal in most cases) barrel, the shot
does not disperse significantly until some finite distance from the barrel.
Until then, the shot is effectively a .72 cal (for 12 gauge) slug with muzzle
energy of 2000-3000 ft-lb.

OTOH, a short .410 gauge shotgun will likely have less muzzle energy (650 ft-lb
typical for slugs) than a max .45 Colt (410-840 ft-lb -- using comparative
figures for a multi-purpose [.45 Colt/.410 shotshell] Thompson/Center Contender
handgun) or typical .44 magnum (1100-1600 ft-lb) load, and slightly more than a
..45 auto (350-530 ft-lb). A 16 or 20 gauge shotgun will, obviously, be
somewhere in between (1400-2000 ft-lb).

I suppose I would worry most about a short-range "clean miss" with a 12-gauge
and buckshot -- it would make a BIG hole. Also, I would worry about ANY miss
with ANY firearm -- the potential for injuring innocent passengers is high
(though more acceptable than crashing the airplane and killing everyone).
However, longer-range "misses" with smaller-size shot would be less likely to be
lethal or damage-producing, and may be stopped by a seat back or partition.

OTOOH, I have seen evaluations of shotshells in .357 and .45 Auto caliber in
handgun loads. They are much less effective than any solid bullet load against
clothed bodies.