Barrels are a required component of all guns. All guns require a gun core, a heatsink, and a barrel to be linked in order to be used; these may be unlinked at any time. Barrels can naturally be obtained by unlinking complete guns, which can be found in Central Control, in the two desks in the southwestern office. In other sectors, security offices can contain any basic weapon, including complete guns and barrels.
Barrels can be researched and then produced at the 3D Printing System. Once researched, improved variants can be produced and subsequently researched. Improved barrels sport a higher chance of dealing a critical hit, and high end barrels eventually gain a laser sight and a silencer, but have a higher linking cost (essentially requiring better gun cores, which have the link capacity).