ORIGINAL: oldelkhunter
They are made specifically for a rifle chamber and bore dimesnsions....Each guide will have the cartridge it is intended for put on it. FIrst rate quality and they have a insert that keeps the cleaning rod centered. Is it Anal ? Yes Is it necessary ? When your cleaning a quality barrel.
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...