I Guess I'm an Idiot, Need Help, In-Line Fill w/Gauge

Hey Guys,
I have been searching (obviously wrongly doing so) for a way to install a open and close valve with a gauge in-line .
This will be used in between the compressor out line to the fill line into the gun.

I know the gun has a gauge, and so does my compressor, but the gauge is on the end of guns tank and is Very small, and i sure as hell do not trust the gauge on the compressor..

I do have a couple of omega tanks, but the gun i am filling is a 350 bar gun, i know, i know, i'm Not trying to fill it to 350 but i am filling to 300 and that is a one time deal with my tanks , next fill after is 250ish so i am using the compressor to gun direct

any input would be greatly appreciated
 
i got this valve on ebay for 40 bucks .. it has 1/4 threads so needs a couple of 1/4 to 1/8 adapters and an 1/8 T hydraulic fitting for the guage .. couple of 1/8 fosters and a couple of hoses made up to facilitate connection .. i use it every time to fill ... the bleeder only bleeds the 'out' side with the valve closed ...

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