An additive manufacturing system configured to a 3D print using a metal wire material includes a drive mechanism configured to feed the metal feedstock into an inlet tube and a liquefier. The liquefier has a chamber configured to accept the metal feedstock from the inlet tube. The metal feed stock is heated in the chamber such that a melt pool is formed in the chamber. The liquefier has an extrusion tube in fluid communication with the chamber, the extrusion tube having a length (L) and a diameter (D) wherein the ratio of length to diameter (L/D) ranges from about 4:1 to about 20:1. The system has a platen with a surface configured to accept melted material from the liquefier, wherein the platen and the liquefier move in at least three dimensions relative to each other. The system includes a regulated source of pressurized inert gas flowably coupled to the liquefier and configured to place a controlled positive pressure onto the melt pool sufficient to overcome the resistance of the extrusion tube such that a part may be formed by the extrusion of the liquidus metal along toolpaths defined by the relative motion of the liquefier and the platen.