The AMT Backup was first known as the OMC Backup. This early variant was produced in .380 ACP caliber in El Monte, California. OMC produced a short run of these pistols before the tooling was purchased by Arcadia Machine & Tool, who took over production. The original AMT Backup was produced with a single-action trigger mechanism, while the later "Large Frame" Backup used a double-action-only mechanism. These pistols were manufactured by AMT and later Galena Industries (until November 2001). The AMT Backup line of handguns is now being marketed by High Standard Manufacturing.