A safety device for a medicine cartridge comprising a body for receiving a cartridge, a guard for covering a used needle, a plunger to dispense medicine from the cartridge and a spring for activation of the guard. The trigger fingers of the guard are spaced to avoid or minimize contact with the spring flange during assembly to avoid trigger finger unseating. An elongated trigger finger head enables the device to activate for all known syringe and syringe plunger tolerances. The spring end coils have larger diameter than the inner coils to reduce the likelihood of the spring end coil end interfering with the cartridge subassembly. Syringe capture features are configured to retain a syringe having a small round or conventional cut flange in place during use and reduce the stress on the syringe flange during insertion while maintaining the ability to hold the syringe in place during use.
