You'd have to make the Shotgun effective at long range (slugs? Then it's just an Ironsights sniper) else you'd have to heavy buff its range (which would break it in PvP) Fusion rifles are a little easier to work with. At best, you could cause the damage falloff at range to be dramatic and sudden, and buff the damage strongly in range (which wouldn't really affect PvP). Oh, and the lack of Fusion Rifle crits will always hinder them against damage sponges.