So the idea is very simple for cops.
So for many squad spawns we have access to the combat shotgun as these days criminals are very deadly. However this CS takes away our beanbag shotgun (pump shotgun). Yes the pump shotgun has a lethal alt but cmon we all know its dog shit in lethal PVP due to rate of fire.
So I think it would be fair if the CS shotgun for squads had an ALT fire mode (like pump shotgun) which activated the bean bag rounds to slow criminals. So primary fire is lethal and secondary fire (alt) is bean bag. This should only be permitted for squads.
Also trainees, PC spawns, State trooper and wardens should only have pump shotgun. Not be permitted the CS ALT fire ability as suggested, as only squads should be allowed this.
EDIT: Adding suggestion by riley. If you want to change between lethal and beanbag ammo on the CS you would need to wait 5 seconds. Its not an instant change.