A medicament delivery device is presented having a housing with a proximal end and a distal end, a medicament container arranged within the housing, a biased delivery member cover associated with the housing and movable in relation to the housing, a biased plunger rod associated with the medicament container and movable in relation to the housing, a tubular rotator associated with both the delivery member cover and the biased plunger rod, and a cap assembly associated with the housing, wherein a gap is defined between the proximal end of the biased plunger rod and the stopper of the medicament container when the medicament delivery device is in an assembled state, and wherein the proximal end of the biased plunger rod is in contact with the stopper of the medicament container when the medicament delivery device is in a calibrated state.