I need to replace the factory FCG in my milled Arsenal M7 and KVAR is out of the parts. Whats the difference between the stamped FCG and the milled FCG?? Can they interchange (especially the hammer)???? I posted an ad in the WTB section with no luck though I am surprised no one put an aftermarket FCG in thier milled M7 and still has the original parts. In reality I just need the hammer. Any help would be appreciated.