An injector, comprising: a housing; a container portion disposed within the housing, defining a fluid chamber containing a medicament, and including a plunger moveably disposed therein and defining a portion of the fluid chamber; a firing mechanism including a ram biased against the plunger; a pair of latches moveably disposed within the housing and configured to engage a portion of the ram; a trigger moveably disposed within the housing between a ready position wherein the pair of latches is held in engagement with the portion of the ram and a firing position wherein the pair of latches is released, permitting movement of the ram such that the ram is biased against the plunger by an energy source; and a safety member that is positionable relative to the housing so as to restrict movement of the trigger into the firing position characterized by a guard (66, 166) extending distally of the housing, the guard (66, 166) being retractable with respect to the housing from a protecting position to an actuating position, wherein retraction to the actuating position causes a portion of the guard (66, 166) to move the trigger into the firing position, wherein the safety member (80, 136, 158) restricts movement of the trigger mechanism into the firing position by preventing movement of the guard (66, 166) into the actuating position; wherein the housing includes an opening (15, 144) formed therein, and wherein the safety member (80, 136, 158) includes a blocking member (142, 162) having an end disposed within the housing so as to abut a portion of the trigger, the blocking member (142, 162) extending through the opening (15, 144) of the housing and attaching to a body portion of the safety member (80, 136, 156) that is disposed outside of the housing, and wherein the blocking member (142, 162) is retained within the opening (15, 144) in the housing by a snap fit and is configured to be removed by a user to permit movement of the trigger into the firing position. a housing; a container portion disposed within the housing, defining a fluid chamber containing a medicament, and including a plunger moveably disposed therein and defining a portion of the fluid chamber; a firing mechanism including a ram biased against the plunger; a pair of latches moveably disposed within the housing and configured to engage a portion of the ram; a trigger moveably disposed within the housing between a ready position wherein the pair of latches is held in engagement with the portion of the ram and a firing position wherein the pair of latches is released, permitting movement of the ram such that the ram is biased against the plunger by an energy source; and a safety member that is positionable relative to the housing so as to restrict movement of the trigger into the firing position characterized by a guard (66, 166) extending distally of the housing, the guard (66, 166) being retractable with respect to the housing from a protecting position to an actuating position, wherein retraction to the actuating position causes a portion of the guard (66, 166) to move the trigger into the firing position, wherein the safety member (80, 136, 158) restricts movement of the trigger mechanism into the firing position by preventing movement of the guard (66, 166) into the actuating position; wherein the housing includes an opening (15, 144) formed therein, and wherein the safety member (80, 136, 158) includes a blocking member (142, 162) having an end disposed within the housing so as to abut a portion of the trigger, the blocking member (142, 162) extending through the opening (15, 144) of the housing and attaching to a body portion of the safety member (80, 136, 156) that is disposed outside of the housing, and wherein the blocking member (142, 162) is retained within the opening (15, 144) in the housing by a snap fit and is configured to be removed by a user to permit movement of the trigger into the firing position.