A pressure jacket for use with a fluid injector includes a barrel having a distal end, a proximal end, and a sidewall extending between the distal end and the proximal end along a longitudinal axis. The pressure jacket includes at least one engagement member protruding from a terminal portion of the proximal end of the barrel in a proximal direction along the longitudinal axis. The at least one engagement member tapers axially in a direction from the distal end toward the proximal end of the barrel. The at least one engagement member engages with a locking mechanism on the fluid injector to releasably lock the pressure jacket with the fluid injector. A taper of the at least one engagement member rotationally guides the barrel into self-alignment with the locking mechanism and axially ejects the barrel upon rotation of the barrel about the longitudinal axis.