from my personal exp, gas guns dont work well in cold weather at all.
AEGs have batt problems as well (so make sure they are fully charged etc)
I remember a game i went to in brampton. my m16 seized on the first shot of the game (since the aeg was exposed to cold for about 30 mins b4 the game started and the batt didnt have the power to cycle the gun) so i pulled out my pistol and charged up the middle hoping to at least be a distraction so my teammates could flank them. Pop Pop Pop, on the third shot, my valve locked open and all my gas emptied. All everyone sees is a big Cadpat guy in the middle of the field, with no primary, and a gas pistol with a huge cloud of white gushing from the slide. At this point, i pulled out my rubber bayonette and charged XD
needless to say it ended painfully for me XD
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