I'm currently in conceptual phase of designing a coil gun. Thinking back to my physics 2 class-- and some of my independent studies-- I understand an EMF produced by a solenoid with current through the wires of it is strengthened significantly by a ferrous core, as seen by the classic experiment in which a copper wire is wrapped around a nail, and the nail becomes magnetized. Would this concept apply to a solenoid wrapped around a hollow iron tube? In other words, would a solenoid wrapped around a hollow iron tube have a stronger EMF as compared to a regular air-coil? Thanks!