We prefer these weights for these muzzle velocities. For two main reasons. Best performance, and reliability. These BB weights will give the optimal range, and feed reliably. Going heavier than what is recommended may cause issues or PME if the magazine is not modified.

450-500FPS = 0.36g-0.40g
400-450FPS = 0.28g-0.36g
330-350FPS = 0.23g-0.25g