Last night i installed a vent liner into a CVA hex head breech plug. The job was not done the way i have done dozens and dozens of others. In this case an attempt was made to install a vent liner using minimal tools. The method used was a first for me. A machinist would not do the installation in this fashion. A pianist might or perhaps a pharmacist, or carpenter would use this method. First step was to make some sort of a jig to hold the plug centered under the drill press. This block of wood has a mortice chiseled into it so a 12mm wrench can be used to keep the breech plug from spinning.
The block was clamped to the drill press, and a 5/8" hole drilled.
Then the plug was dropped into the hole, a 5/32" was chucked, lube was applied, and a 5/32" hole was drilled all the way through the plug.
Then the 5/32" drill was replaced by a # 4 1/2 eighty two degree center drill; the drill was lowered until it contacted the plug, and the depth gauge on the drill press set to 3/8".
The center drill then was used to drill a 3/8" diameter hole 3/8" deep in the end of the breech plug.
The belts were disconnected on the drill press, the center drill removed, and a 10-32 tap was chucked.
The vent to be installed has about 6 thread.
The chuck was marked with the blue line so rotations could be counted whilst threading the plug. Eight rotations were made to insure the vent would fully seat.
Beautiful presentation Ron ,that's just about the setup I used when I did one of mine after checking out your first tutorial on how to do the CVA plug. But I'm still using the plug you sent me one of the first plugs you had made and haven't had to try my homemade yet, and it doesn't seem like I'll have to any time soon.
Over the years that have passed since this thread was posted, dozens of breech plugs have been modified. One thing changed, due to ease of acquisition, from the method described, is using a 3/8" 82 degree spotting drill instead of the # 4 1/2 center drill.