I have a variant of the High Standard Double Nine called the "Camp Gun". It's a nine shot DA with 6" barrel and a very nice, adjustable, rear target site with a wide 'shark fin' front blade. It has a very nicely fit & finished set of smooth hardwood target grips. The gun came with two interchangable cylinders. The one chambered for standard .22 calibers is fluted, the other is chambered for .22WMR and is not fluted. The fireing pin on mine appears to be free floating in the frame and is not attached to the hammer. The face of my hammer is smooth. Though I cannot say for sure it may incorporate some type of safety system similar to a transfer bar safety which allows the hammer to strike the fireing pin only when the trigger is pulled. Sorry I can't help with a picture or diagram. It is very accurate, seems well made and I enjoy shooting it very much. If memory serves me, I payed around $125 for it when I purchased it 2nd hand back in '85 or '86.
Brett