AMT AutoMag II
Semi-automatic pistol
The AMT AutoMag II is a semi-automatic handgun chambered in .22 WMR, that was manufactured by Arcadia Machine and Tool from 1987 until 1999, and was manufactured by High Standard until their closure in 2018.
The AMT AutoMag II was the first of three semi-automatic handguns that were chambered in the .22 WMR cartridge before the introduction of the Kel-Tec PMR-30 in 2011; the others being the Grendel P30 (1990-1994) and the Excel Arms MP-22 Accelerator Pistol (early 2000s-2023).
01Design
There were a number of engineering challenges to overcome in designing an autoloading .22 WMR handgun such as extraction problems. The extraction problems stem from the fact that the slow burning rifle powder of the .22 WMR cartridge develops a late peak pressure. This can cause the case mouth to expand and jam in the chamber when fired from a handgun. AMT overcame this issue by drilling 18 holes at 90 degrees to the chamber. A sleeve was then welded over the chamber; providing a tiny amount of clearance for the excess gas to escape from the first set of holes on back to the second set, thereby relieving the pressure enough to prevent the case from sticking.
The stainless steel slide has a large cutout over the barrel, similar to the Beretta M9, to facilitate better cooling and ejection of the spent brass casing (more likely it is simply to reduce the moving mass of the slide to allow for the blow-back operation). The stainless steel construction throughout makes rust a non-issue.
Sources and credits
This article is adapted from the Wikipedia article “AMT AutoMag II”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
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