Modular polo mallet head design

Just got some new shafts and don't want to have the problems I've had before (nut pulling out/shaft cracking at the seam). Is there an optimum length to cut off the bottom of the shaft so that an M5 nut slides down far enough, but not too far?

I did UTFS but couldn't find anything.

Insert the nut first, pull it tight, then cut so whatever bolt you have fits into the nut with 1cm to spare (for the head, and to tighten)