CO2 air gun

I am trying to make a co2 air gun and was wondering if jb weld can hold the pressure from the 12g co2 cartridge in this set up with a co2 bike pump connected to a valve that can wothstand the pressure

 

i havent put the jb weld on yet, i will put it on the red threads then screw it in after i know it can withstand the pressure.

 

This co2 bike pump can pump out air at different rates, i want to use this for an air gun but i am a bit unsure about the amount of pressure that my parts can handles so i want to stay within 100-150 psi and co2 is like 850psi, so if i use this bike pump and open it like a quarter turn or something, can i achieve a lower psi or will the chamber it's releasing co2 into just fill up to 850psi more slowly
https://www.amazon.com/Portland-Des...&qid=1464059569&sr=8-5&keywords=co2+bike+pump