The embodiments disclosed herein relate to lockable syringe assemblies and related devices and methods. The syringe assembly may include a barrel, a plunger, and a locking mechanism. In some arrangements, the locking mechanism is an elastomeric locking ring or a rigid partial ring. The plunger may include a plurality of ribs and is longitudinally moveable within the barrel. Once the plunger is disposed at a desired longitudinal location, the plunger can be axially rotated and locked in such a way that further longitudinal movement is restricted.