I know, call Best fittings, but it's sunday and i'm pondering. I want to be able to measure the cylinder pressure of a rifle while shooting. That's no issue, i could put a QF onto a gauge and leave it on the gun. But I also want to use the same gauge when I fill. So what I want is some sort of tap, that I can put upstream of the gauge in between gauge and dive bottle, close it after filling, purge the line, disconnect and the gauge not to budge. Effectively like another bottle tap, only not so expensive and difficult to connect. Does such a thing exist considering we're talking 2-300 bar?