Bioshock Infinite Weapons & Upgrades: Pig Volley Gun, Paddywacker Hand Cannon, Peppermill Crank Gun

Pig Volley Gun
Minimum Damage: 550+200     Upgrades:
Maximum Damage: 650+250       Damage Boost 1: $522: +25% Damage (Finkton Docks)
Critical Multiplier: N/A                Damage Boost 2: $522: +25% Damage (Downtown Emporia)
RPM: 120                         Radius Increase: $536: +50% Blast Radius (Downtown Emporia)
Magazine Capacity: 8                  Clip Increase: $740: +4 Clip (Downtown Emporia)
Reserve: 24

This gun lobs explosive shells at its target. This gives it a unique mode of fire and makes it so you can fire behind whatever cover your foes may have taken. It also has splash damage which, of course, degrades farther from the point of explosion. It deals great damage on its own and, thanks to its small burst radius, can work as a substitue for the shotgun. It has a good reload and works best with direct shots over counting on the blast radius.

Paddywacker Hand Cannon
Minimum Damage: 510     Upgrades:
Maximum Damage: 690       Damage Boost 1: $448: +25% Damage (The Factory)
Critical Multiplier: 3              Damage Boost 2: $448: +25% Damage (Emporia)
RPM: 75                              Reload Increase: $656: +50% Reload (The Factory)
Magazine Capacity: 6            Recoil Decrease: $350: -20% Recoil (Downtown Emporia)
Reserve: 18

If you want to kill something at close range with a single shot, this is your gun. It has low accuracy and a slow rate of fire but its damage is immense for a pistol. Combo this with Shock Jockey to stun your opponents, fire a few shots into them and they will be down for the count. Just remember that you have to make every shot count save for when this gun is fully upgraded.

Peppermill Crank Gun
Minimum Damage: 70
Maximum Damage: 130
Critical Multiplier: 1.5
RPM: 1500
Magazine Capacity: 100
Reserve: 100

This is a gun that does not need any upgrades, as Gatling Guns rarely need them. You also will not really be walkign around with it long. This gun is mostly found from destroying the Motorized Patriots who use them. Just grab it, unload it on the nearby enemies to turn them into salsa then let it go. More likely than not you will have used the majority of your ammunition in that time frame.