Has anyone tried it with protected 18650 cells? The length of the cells should fit (69-72 mm), but will the pins in the head and back fit?

It is not clear how wide the pins are, I mean the radius of the circle on which they are spaced around the center.

There is a suspicion that they will not touch the contacts of 18650. This question is because a friend is going to buy 700fd at a local internet store, but he is reluctant to spend money on 21700, he has a lot of protected 18650. Side rattle is not a problem, the cell can be wrapped with several banknotes