High Quality Content by WIKIPEDIA articles! The Ruger SP-101 is a series of double action revolvers produced by the American company Sturm, Ruger. The SP101 is a small frame and all-steel construction carry revolver, with a 5-shot (.38 Special, .357 Magnum, and 9x19mm Parabellum), 6-shot (.327 Federal Magnum and .32 H R Magnum), or 8-shot (.22 LR) cylinder.