The BuckMark series, introduced in 1985, encompasses various models such as the BuckMark Plus, BuckMark Silhouette and BuckMark Varmint. The Challenger II was produced from 1976 to 1982, followed by the Challenger III from 1982 to 1984. These models feature variations in magazine release mechanisms, including those located at the bottom of the firearm and those positioned behind the trigger guard. Our magazine is compatible with all models in the series.