An alignment assembly for a cartridge interface of a drug delivery device is disclosed. The assembly optionally includes a coupling for opening fluid communication between the cartridge and the delivery device. For example, the coupling optionally includes a cannula insertable through a septum of the cartridge. The assembly may include a guide for positioning the cartridge and/or an access channel thereof within a first precision of a loaded position. The assembly optionally includes a cartridge engagement fitting (for example a gripping expander sleeve collar) attached to the coupling. Optionally when the cartridge is engaged to the fitting, the coupling is retained in connection with the access channel to within a second precision. The second precision is optionally higher than the first precision. In some embodiments one or more compliant supports movably retain the fitting oriented to engage the cartridge when the access channel is in the loaded position.