This month has seen 2 different deer seasons. First one was an early doe season; second a muzzle loader season. Next month starts our general rifle deer season. This morning was a time for me to shoot the rifles i planned to use this upcoming season. The early doe season saw me use the 45 Knight Disc Elite successfully. It shoots a long way that rifle does. The muzzle loader season that ended yesterday required iron sights, and the X7 was used; results were good. This morning i tried out the 50 Knight Disc Extreme, and an X7 that is scoped.

Returning home, the Knight was cleaned, and whilst the new NFPJ breech plug was removed, i measured the flash hole. The flash hole measured 0.035". I counted the primers fired in this plug, and came up with 106. This is the second NFPJ plug i purchased from the new Knight. The first plug' flash hole showed 0.035" when i cleaned it after 108 shots. In the first plug i replaced the brazed vent liner with one made from Holo-Krome screw. In the above photo, the modified first plug is shown right of the newer unmodified plug. One can see the flash hole in the unmodified plug is definitely larger than the flash hole in the home made vent liner. As written before, the flash hole in the plug on the left is now 0.035". The flash hole in the plug on the right is 0.028" which is what it was new, and what it is now, after 37 shots.

It was decided to replace the worn vent liner in the new plug. The first time i did this modification, i used a 5/16" center drill to do the job. This preserved the dome effect. Today i decided to use a 3/8" spot drill which would completely remove the brazed in vent liner, and also because it was carbide. It seemed to me the carbide drill would better handle the hard existing vent liner.







One can see in the photo, the damaged cutting edge on the carbide spot drill. These carbide spot drill aren't cheap.







The breech plug was worked with the 3/8" spot drill, and a 5/32" drill, and a 10-32 tap to receive a new vent liner. The photo shows chatter marks left by a dulled spot drill. The Holo-Krome vent liner is shown to the right. It has a 0.028" flash hole. I know from experimentation that a 0.028" flash hole will ignite BH209 at every temperature i have tried. Regular primer will ignite BH from -17 degree up to 95 degree through a 0.028" flash hole, without failure. Larger flash hole are unnecessary, and only lead to a quicker breech plug/vent liner demise.





The last photo shows the newly modified plug, with vent liner in place, left of the plug that was modified quite some time ago. Both vent liner have a 0.028" flash hole at this time. Time and more shooting will reveal how well they survive the heat of ignition.