Originally Posted by BELT_FED

the bolt return spring is heavier and the hammer spring is lighter.. with the blue springs the hole point is to get the bolt to slam harder forward to avoid oobs.. by reducing the hammer spring weight it allows for a heavier bolt return spring... if your having problems romove the hammer spring and bend the legs or clip 1 of them off this will redice the hammer springs resistance on the bolt and allow it to cycle harder... hope this helps