...Spread is an issue I neglected to mention when I listed the weapons, because it's hard to quantify. In short, the shotgun has an "average" spread, the coach gun's is much wider (impossibly wide I might add), and the AA12 has the tightest spread of the 3. To find a niche the Spas would need a variable spread, since how the weapon shoots is the most important element that sets it apart from other weapons.
In short, it's possible, but I have my doubts.
The HS is kind of a paradox with regard to ammunition cost and spread. On one hand you have this relatively heavy shotgun using this hellaciously expensive ammunition, which suggests something along the lines of a "duck/goose" gun, using 3" (76mm) or even 3-1/2" (89mm) magnum shotshells. Perhaps, it may even be a 10-gauge shotgun, as I don't know if the gauge of the HS is officially stated anywhere. That would make the high cost of the ammunition even more logical. A "goose" gun would have a
very tight spread, although would not be suitable for anything resembling buckshot.
On the other hand, this all goes out the window when one witnesses the way the HS patterns it's shot. Shotguns with such "loose" chokes are light, often smaller gauge weapons, used for hunting fast-moving game like quail at close range.
True, large gauge shotguns firing buckshot are quite common, but these weapons provide a relatively dense pattern at something like 40+ meters, otherwise they would be quite useless. As everyone knows, using the HS at anything close to that range is simply a waste of time and ammunition. I'm not lobbying for any adjustments, mind you. It is what it is...
I agree with Judaeus Apella that slugs and sabot rounds would be a nice addition, but, I also appreciate the issues that Pika-Cthulhu ably points out. Seems like we would need a dedicated slug-gun to deal with those concerns. Why bother with another shotgun for Support? A great question. I'd offer that a slug gun would afford the Support types an opportunity to engage targets that are outside the effective range of their shot-based weapons. While many KF maps are close-quarters affairs, there are opportunities for some moderately long-range love on quite a few. Yes, that is properly Sharpshooter territory; I get that. But, on a public server with a pick-up crew of mixed perks and abilities, I'd like the team's Support to have the option of some additional range, if needed.