airsail said..
Every manufacturer measures masts differently, some from the top surface of the mast plate to the top of the fuselage. Others from the top of the mast plate to the bottom of the fuselage, there is no standard.
I never realized that. Seems Axis uses top surface of the mast plate to the bottom of the fuselage, Armstrong uses something else. When measured, the 4 cm difference between a 75 cm Axis alu mast and a 71 cm Armstrong mast pretty much disappears.