Abstract: Milling tools, systems, and assemblies may have an adjustable gauge diameter. An example mill may include a body with tracks thereon. The tracks may slope in an axial direction and may be configured to couple to multiple blades. A locking collar may be positioned on the body and may be movable between multiple locking positions. Each locking position may be axially offset from another. At each locking position, the blades may be located at a different axial position on the body. Where the tracks slope, each different axial positions of the blades may also correspond to a different radial position for the blades. A gauge diameter of the blades may be based on the locking positions of the locking collar.