Due to the nature of CO2, there can be considerable change from one shot to the next due to the CO2's expansion. Rapid firing will make this situation worse because it will cause your gun to get cold which stops the CO2 from properly expanding, so be sure to fire slowly and allow your gun return to ambient temperature between each shot. If you are unable to get your gun to shoot consistently with CO2, especially if the outside temperature is 50 degrees or below, you may want to consider using compressed air.