Ok... Here is what I know today. I have a thread pitch gauge. I am in the fastener industry. I bought Startime, Clark, WO, Otto, Esslinger tubes that are generic. They are .3 pitch. The BP cases/tubes that I have done are .5 pitch.
To confuse you more, I used .35 pitch tap into my BP case and that also worked.
WM9? Can you even buy from him anymore? I use TC.
Summary. Gen should be .3. BP case and tube (the ones I worked on) were .5.
Your mileage may vary. If you start your tube into the case and get resistance, something is fecked up.
Best thing to do IMHO, is evaluate what you have, then proceed accordingly.