There are only 2 things that would make your bb curve that bad (that I can think of anyway). A malfunctioning hop up unit, or resistance in the barrel of some kind, such as debris, or inconsistancies in the barrel finishing. Yes, bb's could cause curving, but not consistantly in the same direction. Look down the barrel and see if everything is consistent and smooth. For hopefully obvious reasons, take the mag out first. If everything looks good, then it is your hop up.
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