One of my friends has the A&K M4 S-System and it's decent. The battery is so-so, which seems to die quickly and has a low ROF. It's pretty heavy, and an alright shooter, but I'd rather use some other brand. I'd like to see how it'd perform with a battery upgrade, but there are still some other small areas of concern with the gun, making those other guns (Echo 1/JG/CA sportline) better choices.
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