Aha! JNH has it right, they aren't using the usual hardware.
According to Pitt's website, their cases use 4-40 screws, 1/4" length. However, they use what appears to be standard Eurorack rails, so it might make better sense to disassemble the rail assembly and substitute some M2.5 or M3 sliders so that the cab now conforms to the usual hardware. And make sure you have more sliders than you think you need, because you'll need more anyway. Eurorack is like that.
I'd suggest checking Befaco's website. Not only do they have the sliders, they also have the "Knurlies". These are available in M2.5 and M3, and they speed up adjustments to a build to a matter of minutes, with no need for a screwdriver.