I am still trying to get everything pulled together to see if conversion is practical for the Jr Gent 1 Rollerballs. It looks like there is a new version of the FP nibs that might work but I'm not sure.
Today I received couplers from my supplier that supposedly work with both FP and RB BUT they don't work with the nibs they sent me when I bought them. I have contacted them with the question that they might have sent the wrong nibs. I will continue to follow up on this until I can give you a definate answer.