if you have a spring, then keep it as such. the only advantage to gas rifles are the realism and ease of turning the bolt, and the huge FPS increase on hot days. i love gas rifles. i love my tanaka kar98k, but because it is gas, i am going to have to buy (like i need an excuse anyway
) an MP44 if i want to play WWII in the cold weather. spring guns can be used in any weather and fire very consistently, which = more accuracy. keep your maruzen as it is.