My Tanaka Kar98k. Before i got mine, i got to use a friends, his clocked at 377 on a spring day with .30g! The accuracy is ridiculous. When i got to shoot it, it when straight and then out of sight because the accuracy and range is so good. While not a cold weather gun, so long as the temp is comfortable, the gun will shoot consistently, accurately and fast. what more can you want right? and since i dont play airsoft in the winter, this gun is a great choice for me. Plus once i join up with the WWII guys, i have a great infantry gun
As for upgrades, i have a scope, just finding a mount, a have the sling and a total of 4 mags (total of 40 shots) which should last me long enough in a game. cause going through 40 shots in one sitting is just nuts. the only performance upgrade i have bought, but not installed yet (as i dont know how) is a KM TN 6.04 mm tightbore. I think i am one of the few people actually have one. Most find the Kar98k to be accurate enough. So think how accurate it will be after i put a 577mm long TB into it =D