K frame may be too tight for a Sec. 6, especially if its has a thumbsnap at the top.
I have both and the holster for my K will not allow the thumbsnap to close with the Ruger in it. The Ruger is also a little tighter fit overall than the S&W.
The Ruger is a lot beefier at the top than the K frame S&W. With an open top holster, it should not be an issue.
I had a Security-Six 4" long ago. I guess I've forgoten how fat it was! I recently had a 6" GP-100 and the 686 holster worked great. I was thinking the Security-Six was a lot thinner. Damn memory is going![]()