OCD
It was really bugging me that I didn't know why the master cylinder on the C10 was acting abnormally. I wanted to know why.
I put a tie-rod end and sleeve on the truck, and then did an inspection on the master cylinder. I found the problem.
continue to find a representative image of what I found on this new/rebuilt master cylinder. click for bigger.
The primary piston was effectively lengthened by not being put together all the way. This pushed the secondary piston pressure seal past its compensating port so it could not fully release front brake pressure. I guess it didn't defy physics after all ;-)