AMT AutoMag II

The AMT AutoMag II is a semi-automatic handgun chambered in .22 WMR. Arcadia Machine and Tool made it from 1987 until 1999, and High Standard made it afterward until that company closed in 2018. It was the first of three semi-automatic handguns chambered in the .22 WMR cartridge before the Kel-Tec PMR-30 appeared in 2011; the others were the Grendel P30, made from 1990 to 1994, and the Excel Arms MP-22 Accelerator Pistol, made from the early 2000s to 2023. The design had to solve an extraction problem, because the slow burning rifle powder of the .22 WMR cartridge reaches its peak pressure late and can make the case mouth swell and jam in a handgun chamber. AMT drilled 18 holes at 90 degrees to the chamber and welded a sleeve over them, leaving a small clearance that lets excess gas escape and ease the pressure. The slide is stainless steel with a large cutout over the barrel, similar to the Beretta M9, and the stainless construction makes rust a non-issue.