My fix for side play on rear sight of my GP100

[toolmaker]

Not liking the side play in the rear sight of my GP100, I found last night that a .004 inch steel shim cut to profile, de-burred, drilled for the retaining pin (shim made from an old feeler gauge), then inserted to one side of the sight base before replacing the sight pin, removed all annoying play. Now the sight base moves smoothly up and down but the side to side movement is gone. Will do my Super Blackhawk today. I a happy puppy...

 

[Z_Infidel]

Even though you have found a solution, you might want to take a look at Bowen's Rough Country adjustable rear sights. IMO they are a big improvement over the Ruger factory sights.

http://www.bowenclassicarms.com/