No, the bottle thread will be the one I have shown, the .85 big 14 tpi. Or else the US GCA320. Not even close to 1/4 BSP.
You still need a connecting nut from 1/4 BSP to whatever on your bottle. The easiest to make (for somebody with a lathe of a good drill press and the tap-set) is a 1/2 bsp female to 1/4 BSP male. So, a on/off valve on the 20oz tank, and you're in business.
Sleightly less easy, as it requires a shop that can crimp hydraulic connectors, is to use the CO2 threaded normal valve, and the hose/connector of a fire-extinguisher. Just crimp on the 1/4 BSP male.
