To resize or change the buckle, remove the Chicago screw. Replace your buckle, or roll the belt from the existing buckle end to the position you need and use the pointed tip of a pencil to separate the braid and replace the screw. Test that the new size is correct then cut off the excess, at least 1.5" (3.75cm) past the Chicago screw, from outside edges toward the center. Burn the ends with a butane lighter to seal. Better, you can use a hot knife, made for cutting nylon, or heat a blade to melt through the nylon. The secret is to seal the end of the braids together, through burning that edge into all of them.
The billet end is sealed under a silvertone tip. This is best left sealed unless you are replacing the tip.