Operations performed by a medicine injector having a barrel with a receiving cavity to slidably receive a syringe subassembly for axial movement therein. Upon removal of a safety and release of a syringe driver, the syringe driver moves forward and injects the syringe needle. One or more penetration controls are shown for controlling injection needle penetration depth. In some forms of penetration control a sleeve and spring are used in the methods performed. This construction and a cushioning piece or pieces may be used to reduce the forces experienced by the syringe subassembly. A load distribution ring may further be used with a cushion, spring and guide ring which may be used to help distribute deceleration loading experienced by the syringe subassembly.
