An injector comprising: a body, and a pathway within the body for receiving a cartridge (28, 28', 28"), the cartridge (28, 28', 28") being one of a plurality of differently dimensioned cartridges, the pathway including a proximal opening for receiving the cartridge (28, 28', 28") therethrough; an injection needle movably mounted to the body, the injection needle being displaceable between a retracted position and an injection position; a cartridge piercing needle projecting into the pathway mounted at a distal end of the pathway and in fluid communication with the injection needle, the cartridge piercing needle being configured to engage the cartridge (28, 28', 28") for fluidly connecting the cartridge (28, 28', 28") with the injection needle; and an adapter collar (30, 30') mounted within the distal end of pathway, the adapter collar (30, 30') configured to receive the cartridge (28, 28', 28") therethrough upon insertion of the cartridge (28, 28', 28") into the pathway and configured to engage a portion of the cartridge (28, 28', 28") to stabilize the cartridge (28, 28', 28") within the pathway, the adapter collar (30, 30') comprising a disk and fingers that are cantilevered, that are angularly spaced apart from each other, and that project from the disk, the fingers being oriented in an unbiased, radially inwardly projecting closed position covering the cartridge piercing needle, and the fingers being deflectable distally and radially outwardly relative to one another by the cartridge (28, 28', 28") into an open position exposing the cartridge piercing needle upon advancement of the cartridge (28, 28', 28") through the disk. a body, and a pathway within the body for receiving a cartridge (28, 28', 28"), the cartridge (28, 28', 28") being one of a plurality of differently dimensioned cartridges, the pathway including a proximal opening for receiving the cartridge (28, 28', 28") therethrough; an injection needle movably mounted to the body, the injection needle being displaceable between a retracted position and an injection position; a cartridge piercing needle projecting into the pathway mounted at a distal end of the pathway and in fluid communication with the injection needle, the cartridge piercing needle being configured to engage the cartridge (28, 28', 28") for fluidly connecting the cartridge (28, 28', 28") with the injection needle; and an adapter collar (30, 30') mounted within the distal end of pathway, the adapter collar (30, 30') configured to receive the cartridge (28, 28', 28") therethrough upon insertion of the cartridge (28, 28', 28") into the pathway and configured to engage a portion of the cartridge (28, 28', 28") to stabilize the cartridge (28, 28', 28") within the pathway, the adapter collar (30, 30') comprising a disk and fingers that are cantilevered, that are angularly spaced apart from each other, and that project from the disk, the fingers being oriented in an unbiased, radially inwardly projecting closed position covering the cartridge piercing needle, and the fingers being deflectable distally and radially outwardly relative to one another by the cartridge (28, 28', 28") into an open position exposing the cartridge piercing needle upon advancement of the cartridge (28, 28', 28") through the disk.