A fluid infusion device, for delivery of a medication fluid to the body of a user, includes a housing, a fluid reservoir for the medication fluid, a dosing mechanism, an infusion component, and a mechanical actuator. The fluid reservoir and the dosing mechanism are located in the housing, and the dosing mechanism is coupled to receive the medication fluid from the fluid reservoir. The dosing mechanism has an adjustable fluid chamber that defines a variable dosage volume. The infusion component is coupled to the dosing mechanism to receive the medication fluid from the adjustable fluid chamber. The mechanical actuator is coupled to the dosing mechanism such that operation of the mechanical actuator causes the medication fluid to be expelled from the adjustable fluid chamber to the infusion component.
