i have a green gas rifle and was told by 3 forums and one local store to always leave a little gas in the mag. now i went to another local airsoft store and i spoke to a 30 year veteran of co2 and green gas. he has been playing airsoft since it started and makes a LIVING selling and servicing these guns, he even services the guns on all 200 memebers of his airsoft club/team. so with all this exsperiance i thought he would tell me the same thing about storing alittle gas in the mag. when done. to my serprise he said the oppisite!! he told me it in this way and i quote " never keep any preasure of gas AT ALL in the mag. that the preasure just sitting there will cause seal damage and then he brought up two good examples first he said think about this way, even though c02 and green gas are differant gases, the preasure is the same, and by leaving preasure in the gun (of a co2) which has the same rubber seals) is not good, now we all know that you should never leave even a little gas in a co2 so why leave it in a green gas mag.? coper bb guns use co2 and the companys that make them ALWAYS say not to store a bb gun with preasure of a co2 in it, then he said this, the day a manufactuer finishes making a green gas mag. do they put a little gas in it? no, that mag. can sit for a year or two before it makes it from the plant being made to being ordered by the store and then the store keeping it on the self for a while before me and you buy it. so does the seal get damaged? no if anything after you and i use it it has a little bit of microscopic gas in it even empty. and we all know that green gas is made of propane and SILICONE which will protect the seal anyway.then he went on to say that who do i know that ever experimented on never leaving a little gas in it for storage, no one, we all were always told to leave a little gas in it. so maybe this is why we replace seals in our magz. ever year or so due to the preasure always damaging the seals. well i have to say the idea he brought up about the copper co2 bb guns (that have been around before airsoft) that makes sence cause i was always told never to leave any gas co2 wheather a lttle gas in it or not in a bb gun, the preasure wil ruin the seal and i remember doing that has a kid and a year or so later the seal was really ruined. and another thing the seals in a mag is always lubed up from damage cause we always spray silicine oil on thenm after use for the day.
here is a link on that:
http://www.ehow.com/how_2302319_use-co2-bb-gun.html
and this link proves that your magz. seals are being lubed anyway