Shotguns are my favorite real world firearms, being less of a conventional "gun" and more of a "payload delivery system" capable of being loaded with everything from rock salt to explosive slugs. But I have a hard time swallowing Shadowrun's Shotgun rules.
Real world, a 12 gauge slug works out to about 18mm in diameter and leave the barrel at around 1600 fps (this actually means they are faster and heavier than many .45-70 gvt. loads and deliver 50-100% more energy than most modern assault rifle rounds) Being typically bare lead or hollow/ballistic point, they expand rapidly and do tremendous amounts of damage.
In Shadowrun, the shotgun does barely any more damage than a rifle without even half the range. Shot is considered nearly worthless to the point they only have Flechette rules which grant insane bonuses to enemy armor (ignoring the fact that one of those darts might just slip though an unprotected area..) Essentially they've completely removed any and all advantage the shotgun holds in real life without providing a good reason to use one.
So it boils down to this, is there any reason to even have these in the game and not just give all shotguns some arbitrary reference?