I have a WE flock 18c works fine I have a small mag and a extended mag I find if I fill the mags up at the start of the day say 10!in the morning if I go to use the side arm at say 12 most of the gas has escaped, the mags hold gas when not in use, is this a common thing or do I need to tighten some thing or change a o ring or ptf tape some thing cheers lads