I remember Will Q saying exactly the same thing. When he was modding those lights each thread was cut to fit the existing thread on the body. Not too hard when doing one at a time customs but a real challenge if trying to make a quantity of parts.... the threads are very sloppy on MagAAs so don't let it fool you if trying to measure directly on a MagAA.
From my measurements i found the Mini-maglite bezel ring threads to be 28tpi rather than the 20tpi of the Surefire E-series bezel rings.