Hap,
You might think about a variation on Cush's suggestion. Remove the insert nuts, drill thru the forend with a drill a little smaller than the insert nut diameter, taking care not to enlarge the hole for the insert nut. Get a walnut dowel a little bigger than the hole you drilled, cut off a piece about an inch long, put it in an electric drill or your lathe if you have one, and sand it to fit the hole you drilled. Cut off the appropriate length you need and glue it in below the surface enough to allow for the lenght/depth of the insert nut. When it dries, drill the clearance hole for the screw to pass thru and glue in the insert nut. You'll be crushing against endgrain of the dowel and it'll resist crushing much better.
