Two Birds, One Bullet lets your shots pierce through more targets. It is a Tier 5 Ranged skill that is great against Hordes, where Freakers line up in narrow spots.
Yes, if you plan to clear Hordes. It saves a lot of ammo.
Iron Grip, Up The Ante and Head Rush.
Fight Hordes from a doorway, bridge or narrow path. The tighter the line, the more each shot hits.