Sorry to revive an old thread.
Can anyone confirm that a .050 driver fits the PolyPro pinion set screws? I have two of these and have tried two different high quality .050 drivers and both are a loose fit. I contacted 17.5RC and they insisted that .050 was the correct size and would not tell me the thread size of the set screw. I even took the pinions back to the shop I purchased them at. They tried every driver they had metric and standard and not a single one fit properly. Thanks in advance.