Actually, there a three different items being seen in these pics. All pics of the gun show the early S&W grip adapter, which was an elaborate device mounted under and retained by the stocks. The pic of the gun depicting the initials in the stock show the gun mounted, right side, by a muzzle post and a hook under the rear of the trigger guard. The third picture showing the gun mounted on the left side with the description underneath, appears to be a secure mount around the trigger guard, probably from a mobile display.
I once saw Patton's .357 on display at a Birmingham gun show several years ago and it appeared to be securely locked into that display case, for obvious reasons. It was also displayed with his General Officer's belt & holster rig. Quite an impressive looking firearm, with all it's history!