An autoinjector comprising: a case a syringe carrier slidably disposed within the case, the syringe carrier adapted to hold a syringe including a stopper; a plunger slidably disposed within the syringe carrier, the plunger adapted to apply a force on the stopper; a drive spring disposed within the plunger and biasing the plunger relative to the syringe carrier; a needle shroud slidably disposed within the case, the needle shroud telescopically arranged over the syringe carrier; and a detent mechanism adapted to (i) couple the needle shroud to the syringe carrier and (ii) adapted to couple the needle shroud to the case wherein the detent mechanism comprises a resilient shroud beam (7.2) on the needle shroud having a shroud boss (7.1) releasably engaging a carrier opening (8.6) in the syringe carrier, characterized by: a collar slidably arranged on the syringe carrier; and a control spring applying a biasing force to the collar, wherein the collar includes a resilient collar beam (16.2) having a collar boss (16.1) adapted to releasably engage a step (8.5) on the syringe carrier, wherein the collar boss (16.1) is prevented from deflecting radially by a narrow section (2.4) in the case, wherein a wide section (2.5) is arranged distally from the narrow section (2.4) such that upon axial movement of the syringe carrier and the collar in the distal direction, the carrier boss (16.1) deflects radially when the collar enters the wide section (2.5) and disengages the collar from the syringe carrier under force from the control spring allowing the collar to advance further under the force of the control spring until it abuts the needle shroud. a case a syringe carrier slidably disposed within the case, the syringe carrier adapted to hold a syringe including a stopper; a plunger slidably disposed within the syringe carrier, the plunger adapted to apply a force on the stopper; a drive spring disposed within the plunger and biasing the plunger relative to the syringe carrier; a needle shroud slidably disposed within the case, the needle shroud telescopically arranged over the syringe carrier; and a detent mechanism adapted to (i) couple the needle shroud to the syringe carrier and (ii) adapted to couple the needle shroud to the case wherein the detent mechanism comprises a resilient shroud beam (7.2) on the needle shroud having a shroud boss (7.1) releasably engaging a carrier opening (8.6) in the syringe carrier, characterized by: a collar slidably arranged on the syringe carrier; and a control spring applying a biasing force to the collar, wherein the collar includes a resilient collar beam (16.2) having a collar boss (16.1) adapted to releasably engage a step (8.5) on the syringe carrier, wherein the collar boss (16.1) is prevented from deflecting radially by a narrow section (2.4) in the case, wherein a wide section (2.5) is arranged distally from the narrow section (2.4) such that upon axial movement of the syringe carrier and the collar in the distal direction, the carrier boss (16.1) deflects radially when the collar enters the wide section (2.5) and disengages the collar from the syringe carrier under force from the control spring allowing the collar to advance further under the force of the control spring until it abuts the needle shroud. a collar slidably arranged on the syringe carrier; and a control spring applying a biasing force to the collar, wherein the collar includes a resilient collar beam (16.2) having a collar boss (16.1) adapted to releasably engage a step (8.5) on the syringe carrier, wherein the collar boss (16.1) is prevented from deflecting radially by a narrow section (2.4) in the case, wherein a wide section (2.5) is arranged distally from the narrow section (2.4) such that upon axial movement of the syringe carrier and the collar in the distal direction, the carrier boss (16.1) deflects radially when the collar enters the wide section (2.5) and disengages the collar from the syringe carrier under force from the control spring allowing the collar to advance further under the force of the control spring until it abuts the needle shroud.