I know this topic has come up multiple times but I really haven't see any answers posted. I have 2 40 cal mp5's and want to use a 3 lug adapter. Does anyone know if I can take the gemtech 3 lug or liberty 3 lug adapter and bore them? I have all the equipment to do this but I don't want to drop $160 just to find out it want work and gemtech want tell you anything. I don't blame them for keeping quite on it. I know that the piston will have to be opened up to accommodate the larger barrel diameter. I know the lugs are the same dimensions and the only difference between the barrels is only about ~.05. I have had one person tell me that they just had their barrels turned down to fit the 9mm adapter. I would rather modify the adapter and not the guns. I will take any input at this point. Has anyone done this? If not.... If some one could post the inner id and wall thickness of a 9mm gemtech 3 lug piston and maybe if some one has a raptor 40 piston could do the same. I think this will give me my answer.