NiCd tend to do a lot better in the cold than NiMh, but a high mAh NiMh pack is fine (3000+) Plastic parts can break more easily, snapped M4 grips, broken plastic hopup units, etc.
I played in -36'C two winters ago (NOT recommended) and my spring M24 was useless as the hopup rubber was solid. My 390fps G36 with 4200mAh battery was fine, fired around 1500rnds that day all on full auto. Cheap classic army pistons will have a much higher rate of stripping as they are made of a brittle plastic to start with. I see an AK in your sig, probably one of the best winter guns. Large battery, solid ver.3 mechbox, the grip is supported by metal underneath (the motor mount), only issue might be the hopup but then thats only when its really cold. M14, so long as its a TM or TM clone, should also do fine in very cold temperatures. G&G and CA M14's can have the stock snap off where you hold the gun. That same day I played in -36'C one guy shattered a G&P tappet plate (the old crappy ones), one guy had massive hopup problems (rubber got hard when it got cold), and one guy snapped a TM MP5k plastic body.
I read on the PTW forums, apparently brass barrels, since they have a higher expansion/contraction rate than stainless steel barrels with temperature fluxuation, sometimes can jam for no reason when using less than absolute top quality BB's (like TM, BB Bastard, etc.) This effect was run into when players got custom DOFF barrels and where playing in the Swedish winter. That is also apparently why they don't make brass barrels tighter than 6.04, go stainless or go home.
Last edited by LUTNIT; November 13th, 2008 at 21:00..