If the gas leaks from the charging valve, it may be loose, or you could try removing the valve and adding some silicone grease to the seal. It's best to keep the mags charged when not in use as the gas also lubricates. I am not an expert on these guns, but have a bit of experience with kjw M9 pistols. I have got parts of the web for these just by doing a search for airsoft spares, China seems to be the best. I think the shop was KN mountain or something similar. Best of luck and hope this helps.