I just purchased the current Knight Disc Extreme bare primer conversion kit which consists of a new bolt housing and a new breech plug. You have to remove the firing pin assembly from your old bolt and screw it in the new housing. The breech plug you get is made by Lehigh for Knight and is identical to the one that Knight sold with the previous bolt adapter/bare primer breech plug kit which I had installed in 3 Disc Extremes about 18 months ago. They worked very well; I just wanted to try the new version. The change out just took a few minutes and everything worked until I inserted a Winchester primer in the new bolt and tried to close it to pop the cap and it would not fully close. I realized the primer was not fully seating in the primer pocket and further that you could not eject the primer without a sharp blow to the bolt handle with a rubber hammer. I removed the new breech plug and reinstalled my old one (also a lehigh) and I was able to fully close the bolt and fire the rifle. Knight informed me that a few of the breech plugs they received from Lehign had similar problems and be glad to send me a new one or I could send it to them for repair. All they do is polish it with jeweler's rouge so I offered to fix it my self. I've been using Western Extreme's bore paste on CVS' Safety Baby Cotton swabs to polish the primer pocket. It's already a lot better and another hour it should be fine. IMO the new bolt is easier to place the primer in than the old one.