A U.S. Navy armorer loads a long belt of .50 caliber ammo into the nose turret of an Atlantic Theater Consolidated PB4Y2 Privateer patrol bomber. Very long range aircraft like this variant of the B-24 helped ensure German U-boats had no safe place to surface and recharge their batteries while on patrol in the Atlantic. U.S. Liberators and Privateers are credited with sinking at least 23 U-boats in the course of the war.
The last flying PB4Y2 Privateer airborne over Chino in May 2017. The nose turret was removed when it was used as a fire bomber, starting in the 1960’s. It served in that capacity until 2006. It just went through a thorough restoration and is now on the air show circuit.
The American Warrior 
Did a PB4Y-2 sank a single U-boat?
That must be an exceedingly rare example.