SH vs JB gap measurement variations

I’m considering switching from my Steelheart to a Jailbird. I noticed that the SH lists two gap measurements—one at the top of the tube and one at the bottom—whereas the JB has just one consistent gap measurement. Does anyone know why this is and which option works better? Also, when sizing a JB based on my current SH fit, should I simply average those two gaps to determine my order size? Sorry if this question was answered before.

I can confirm that the gap for MM isn't uniform around the entire circumference. William designs the top part of the gap to be smaller so the cage stays centered and doesn't twist, preventing you from slipping out. Hope this clarifies things!

Thanks. So should I go with my standard lower gap measurement and let him adjust the top one accordingly?