The Cartridge Carrier holds loose cartridges. It is available in tan. X FR 500 4. RAGING BULL 8 3/8. The modular interchangeable component shoulder systems originally known as the Jackass Rig. Were invented by Galco International in 1969. Today, we continue to offer quality and versatility by developing products that enable you to design the perfect system to suit your needs. For example, you may assemble a two-handgun rig, a half harness system, or add tie downs and cuff case to an existing system. The possibilities are endless. We are an Authorized Galco Full Line Distributor.