Trying to Fit Ruger Security Six After-Market Gun Grips

[fishhead1]

This may sound a little dumb- sorry. I recently obtained a pair of unused (still in the box) Jay Scott walnut target grips made for pre-1976 Ruger Security Six 38/357 mag revolvers (after-market grips for pre-1976 Security Six revolvers are as scarce as hens teeth). Anyway, these grips are a very close fit- but not quite close enough. There is gap at the leading edge of the grips that I can't seem to close sufficiently. With a bit of sanding (and a little whittling) on the inside surfaces of the grips, I have managed to close the gap a fair amount, but I'm at the point that I can no longer tell where additional sanding (or whittling) will do any good.
Now comes the stupid question. I used to watch my Dad make gun stocks (for rifles, mainly). I remember he used a blue "die" on the rifle action that showed (when the action was fitted into the stock) where the "high" surface areas on the stock were. These high areas could then be removed so that the action would fit properly in the stock. I thought I would try this procedure on my Ruger, but don't know what this "die" was, or where it can be obtained. Any help would be appreciated

[Bill DeShivs]

You can use Magic Marker or crayon. Soot from a candle flame works well, too. All of it can be removed by wiping with WD 40.

[Scorch]

You can buy inletting black from Brownells or Midway. Marking blue (often called Prussian Blue, although it is not real Prussian Blue) is sold in tubes at many auto parts stores and certainly at shops selling to the machine tools trades.