OMG... ran out fo scope mounts..!!! So I put on a Handi WGRS rear. It don't fit..! The barrel radius is smaller than the sight base, leaves gaps at the sides.
Any one else had this problem? Did you shim the sides of the sight base?
OR... is there a 'different' WGRS for the 158 smaller diameter barrel? Any other 158 peep sights out there?
Why can't anything be simple?
Simply "bed" the site to the barrel.
Coat the base, the barrel and screws with release agent. Then use something like liquid steel, acura glass JB weld etc. Either trim before completely set OR build a tape damn and remove once hardened.
BTW, in case you haven't realized, you also need a different base for these barrels.

Hole spacing is the same but contour is different for the smaller diam barrel. To make matters worse, its a discontinued base too.
This is the base you need:


CW