okay after doing a lot of research i have determined that gas pipe thread fittings are the most complicated thing in the world and have no idea how to proceed
THIS thing inside the thread cap in my left hand is preventing me from connecting it to my gas canister. I can't take it off, I think it's jbwelded on or something, and I can't order "female to male 1/2" brass BSP connectors" because why would those exist.