for all wanting to know the price, it's $50 with lifetime replacement and come with C3 replacement delrine bumper. the bore is 6mm, stock bore is 5.5mm. I can bore from 4.5 to 6.20mm by request. recommend 4.5mm for .177 and 6.20mm for max speed for .30 cal.
this HP VS can fit all FX AG That has a 9.90MM OD VS