The other day, i quit working this plug when it looked like a headless bolt. Today, i went back to work, and milled the flats.







After the flats are milled the threads need work, and this is done with a 'thread chase'. Then i hit the edges of the threads with a wire brush, and emery paper. Now the breech plug is nearly done.








The final step is to 'polish' the primer pocket, which helps with primer removal.





Then on to installing the plug in the rifle, and see if it works. What was desired here was a 'crush' of the STS primer, which makes for a seal, and thus no blow by. The new STS primer measures 0.2935" long.












When the rifle is put into battery with vigor, the STS was 'crushed' about 0.003".

Somehow, this plug was made the right length, the first time. I musta held my mouth just right whilst working it. It was my intention to make it some too long, and then sand the powder end shorter tiny amounts at a time until the desired head space was reached.