I have an adapter for each gun. I was getting more blowback than I liked with the CCI 209M primer as well as the Federal 209A so I switched to Winchester's regular 209 primer(its a slight bit longer than the other 2) and that solved the blowback issue. My reason for the change was because I liked the larger opening for placing the primer in the new bolt. Received the parts Friday and made a quick trip to the range yesterday. Installed the new BP and bolt and could not get the bolt to close completely. Long story short I finally realized the primer was not seating completely(deep enough) in the primer pocket to allow the bolt to fully close. I reinstalled my old Lehigh BP with brazed vent tube and everything worked. I tried the 3 209 primers mentioned above in the new BP and none of them would seat completely in the primer pocket unless I exerted a lot of force pushing down with a short piece of 2 x 4. Needless to say they were hell to get out. Some where in the manufacturing process nobody checked specs etc. Will be in touch with Knight tomorrow. I'll keep you posted on what they say.