A regulator that controls an amount of energy provided to an auto loader for rounds having different gun powder loads is provided. The regulator includes a chamber, and a piston in fluid communication with the chamber. The regulator may further include a throttling valve having a first position in which pressurized combustion gas from the gas port of a barrel of a firearm can flow into the chamber, and a second position in which pressurized combustion gas from the gas port of a barrel of a firearm cannot flow into the chamber. The throttling valve is configured to move from the first position to the second position when pressure in the chamber exceeds a threshold level. The regulator may include an expansion valve in fluid communication with the chamber and arranged to move from a first position to increase a volume of the chamber when pressure in the chamber exceeds a threshold level. The regulator may include a valve including a vent hole, where the valve is in fluid communication with the chamber and is arranged to vent combustion gas from the chamber through the vent hole.