About the Manufacturer:
Arcadia Machine & Tool, or AMT, was a firearms manufacturer from Irwindale, California that produced a line of pistols using the name AutoMag from 1982 to 1995. These semi-automatic pistols carried a name similar to the sole pistol model that the defunct Auto-Mag Coproration had previously produced. But, there is no connection other than the name similarity.
AMT did not fare well in business and eventually went bankrupt. AMT's assets and trademark were sold off and they passed between a couple of different companies until they were finally acquired by the High Standard Manufacturing Company of Houston, Texas. High Standard still produces various models under the AMT brand, based on original AMT designs.
About the Cartridge:
This cartridge was developed just prior to WWII for the military to use in its newly selected Winchester semi-automatic 30 M1 carbine. It is basically a modification of the Winchester 32 Self-Loading round of 1906. It is considered in the same class as the 32-20 WCF round with an effective range of about 150 yards.