5/16x24 AMPCO Touch Hole Liner Screwdriver Type

TRESO touch hole liners are made from the same tough and erosion resistant Ampco alloy as the TRESO nipples. The flash hole is .0625 diameter. The TRESO flint touch hole liner is installed in a 1/4" x 28 thread in the side of the barrel with a wrench. A new model, available in two thread sizes is removable with a screw driver and is handy for interchangeable flint/percussion lock firearms. We recommend anti-seize material be coated on nipple and touch hole liner threads to make them more easily removed. (Specific installation instructions are listed below. )

INSTALLATION INSTRUCTIONS (screwdriver model): For firearms with
interchangeable flint/percussion locks, use 5/16"x24 thread and matching
percussion drum (install drum and percussion lock first for proper location).
Use ¼x28 thread size for touchhole only replacement applications.
Drill and tap breech with appropriate thread and slightly chamfer threaded
hole with 82° countersink. Install touch hole liner with screw driver. Touch
hole liner should be flush with outside of barrel, if not, adjust chamfer.
Check for clearance inside of bore and shorten touch hole liner if necessary