I am not sure, as I have only made cartridge slides, not a whole belt, but I would say it is the weight of 25 cartridges or so that dictates the width. I have not seen a cartridge belt that was not ~2", I think the width helps distribute the weigh of the cartridges , meaning the belt does not try and fold in on itself. You might be able to buy a belt and trim a little of the top and bottom to fit, that would keep the holders centered. Maybe see if you can find one that has the cartridge loops separated in groups of 5 or 6.