The invention relates to a front-end device (1) of an auto-injector (A) for administering a dose of a liquid medicament, comprising- a support sleeve (1.2) with a first screw thread (1.2.1) adapted to engage a housing (2.1) of a back-end device (3) of the auto-injector (A) to attach the front-end device (1) to the back-end device (3) and- an outer sleeve (1.1) mounted onto a support sleeve (1.2) of the front-end device (1) by a second screw thread (1.2.3),wherein the front-end device (1) is adapted to receive a syringe (2) with an injection needle (2.2) and a barrel (2.3) containing the dose of the medicament and wherein the direction of rotation of the first screw thread (1.2.1) is opposite to the direction of rotation of the second screw thread (1.2.3).