A Ruger Security Six has a deeper frame than a K-frame, and the answer is "maybe." I have one K-frame holster, an El Paso Saddlery 1920, loose enough to swallow even a GP100, while a tight one such as my Milt Sparks 200AW will not accept a Security Six. The 200AW will acept a Ruger Speed Six, because the Speed Six has a less beefy top strap, no barrel rib, and lower-profile sights.