Buy the m15a4, Classic army has gone through great luengths to ensure that there gearbox will be reliable, so consequently alot of their stock parts are upgraded out of the box. You can upgrade it to 400fps without any other modification, it has a metal body, and parts that arn't metal should be made of glass fiber.
Heres a link that compairs a tokyo Marui gun and a classic army gun they are different models but the quality is similar. Ooooh tokyo marui older version m4s have bad barrel wobble just and fyi
http://www.arniesairsoft.co.uk/?filn...6c_review6.htm
You have been spooned*