How do you take seat belt buckles apart?

I didi get them apart, there are the two buttons on both sides of the pivot. One comes out, it is taped in with a splined shaft that is small and pretty delicate (don't ask me how I know). I have one apart and am working on a tool to help get them apart without breaking the splined piece in the shaft, as the pin still will not come as the torsion spring will be stuck and will not allow the pin to come put until the broken part is removed, forcing it will only damage the spring.

As per powder coating, the texture looks to be part of the metal stamping, so I'm gonna strip them, POR-15 them, and paint them up pretty like ;)