Sounds interesting but Dewey also have different bore guides for different rifles and calibers. Maybe not as precise but they do a pretty good job of staying o/c in the chamber with the neat fitting O-rings towards the front of the guide and the machined aluminum bushing in the receiver to keep things nice and straight
I have both of them along with Sinclair, MTM and Stoney Point. They are a cadillac and the rest are Yugos . Another plus is the guy runs a business like it is supposed to be run the old fashioned way.