What is the thread size on a sierra pen transmission ? 8mmx1.0 is to small, and 9mmx1.0 is to big. Trying to thread 30-30 brass to accept a sierra trans.
Be careful - there are 2 sizes of sierra style transmissions out there. One takes a 8mm .75 and another takes an 8.5mm x 1 ( I think or maybe .75 also)
I thought of the m8 x.75 but he stated it was larger than 8mm. That left the 8.5 x1. However the tolerances are so sloppy that they measure 8.4 x1 Either tap will work for what you want to do.