Idea shotgun buffs

I feel that shotguns are in great need of a buff. Even a spas struggles to kill full irons where even a famas could kill one in a few seconds. The m590 is too weak - it cant even one shot a full leather. The aa-12 is powerful enough given its rate of fire, but the knockback pushes enemies out of its effective range. The tier 3 shotgun doesn't need a big damage buff, given that it can 2 shot a full iron. And the spas needs quite a big one. It rarely one shots full irons, so there's really no large benefit of it over the tier 3 shotty. Currently, the Barrett does a better job as no scopes are generally still quite accurate. The spas needs to be able to one shot a full iron from a decent range for it to be up there with the ak, p90 and barrett.