Wait a minute... The PCC joints are just 5mm pegs underneath the ratcheting cube part? This... this changes everything.
Holy crap, I never knew those were 5mm pegs under there. I suddenly have a need to purchase a lot more PCC figures.
The pin that holds the blue peg in place is 5mm. Cut away the blue peg *carefully* I stabbed my fingers a few times but there's a 4mm peg underneath and the 5mm head of the pin is snug enough to plug into a 5mm modulator or weaponiser port.