1)semi-auto:one shot one pull. 2)psp mode:first 3 shots semi,4th shot is 3 round burst at your max rate of fire. 3)nxl mode:first 3 shots semi,4th shot is full auto. 4)millennium mode:first 3 shots semi,4th shot ramps at 2bps as long as you maintain 6bps. 5)auto response:1 shot per pull 1 shot per release. 6)full auto:hold down the trigger and shot at your max rate of fire. 7)breakout mode:1st shots full auto as long as you hold down the triger let go it turns to ramp mode.