A securing device for an injection device which receives a syringe, the syringe having a barrel with a proximal end portion and a distal end portion, the proximal end portion having a radially outwardly projecting flange, the flange having a proximally-facing surface and a distally-facing surface, the securing device comprising: a body (50; 60) having a proximal end portion and a distal end portion, the body having an opening in the proximal end portion accessing an interior of the body for accepting the syringe, the body having a radially-outwardly facing outer surface and a proximal end surface, the proximal end surface of the body being configured to contact the distally-facing surface of the flange of the syringe when the syringe is advanced distally into the opening, so that the flange does not move distally past the proximal end surface of the body; and a securing arm (80; 180) having a free end (82; 182), a base end (84; 184), a first portion (86; 186), and a second portion (88; 188), the base (84; 184) end being fixed to the outer surface of the body, the first portion (86; 186) extending radially outwardly from the base end (84; 184) beyond the proximal end portion (52; 62) of the body to form a radial flange clearance (90; 190) permitting the flange to pass the first portion (86; 186) as the syringe is advanced distally into the opening, the first portion (86; 186) further extending proximally from the base end (84; 184) beyond the proximal end surface to form a flange gap (92; 192) between the proximal end surface of the body (50; 80) and a distally-facing surface of the second portion (88; 188), the second portion (88; 188) being located proximally with the flange gap (92; 192) and extending at least partially radially inwardly toward the free end (82; 182) in a rest position of the securing arm (80; 180), the second portion (88; 188) contacting the flange as the syringe is advanced distally into the opening, the securing arm (80; 180) being elastically flexible to permit at least the free end (82; 182) to move radially outwardly relative to the body to allow the flange to pass the first portion (86; 186) as the syringe is advanced distally into the opening, and the securing arm (80; 180) being biased to the rest position such that after the flange passes the second portion (88; 188), the distally-facing surface of the second portion (88; 188) is configured to contact the proximally-facing surface of the flange to prevent the flange from moving proximally past the securing arm (80; 180), characterized in the second portion (88; 188) being located proximally with respect to the flange gap and extending generally circumferentially around the opening in the body and at least partially radially inwardly toward the free end (82; 182) in a rest position of the securing arm (80; 180). a body (50; 60) having a proximal end portion and a distal end portion, the body having an opening in the proximal end portion accessing an interior of the body for accepting the syringe, the body having a radially-outwardly facing outer surface and a proximal end surface, the proximal end surface of the body being configured to contact the distally-facing surface of the flange of the syringe when the syringe is advanced distally into the opening, so that the flange does not move distally past the proximal end surface of the body; and a securing arm (80; 180) having a free end (82; 182), a base end (84; 184), a first portion (86; 186), and a second portion (88; 188), the base (84; 184) end being fixed to the outer surface of the body, the first portion (86; 186) extending radially outwardly from the base end (84; 184) beyond the proximal end portion (52; 62) of the body to form a radial flange clearance (90; 190) permitting the flange to pass the first portion (86; 186) as the syringe is advanced distally into the opening, the first portion (86; 186) further extending proximally from the base end (84; 184) beyond the proximal end surface to form a flange gap (92; 192) between the proximal end surface of the body (50; 80) and a distally-facing surface of the second portion (88; 188), the second portion (88; 188) being located proximally with the flange gap (92; 192) and extending at least partially radially inwardly toward the free end (82; 182) in a rest position of the securing arm (80; 180), the second portion (88; 188) contacting the flange as the syringe is advanced distally into the opening, the securing arm (80; 180) being elastically flexible to permit at least the free end (82; 182) to move radially outwardly relative to the body to allow the flange to pass the first portion (86; 186) as the syringe is advanced distally into the opening, and the securing arm (80; 180) being biased to the rest position such that after the flange passes the second portion (88; 188), the distally-facing surface of the second portion (88; 188) is configured to contact the proximally-facing surface of the flange to prevent the flange from moving proximally past the securing arm (80; 180), characterized in the second portion (88; 188) being located proximally with respect to the flange gap and extending generally circumferentially around the opening in the body and at least partially radially inwardly toward the free end (82; 182) in a rest position of the securing arm (80; 180).