A weapon system having a gun barrel and an in bore air regulation system. The gun barrel has a first end and a second end. The gun barrel has a bore formed therein that extends from the first end towards the second end. The bore is adapted to receive a round. The in bore air regulation system is operably attached to the gun barrel so that the in bore air regulation system is in communication with the bore to regulate air pressure in the bore and thereby control the position of the round in the bore.