Roger,
Remove the sight and use a socket extension or comparative round rod. Clamp the barrel firmly in a padded vise. Lay the socket extension so that it rests cross the dovetail. Hold it in place, and tap it very lightly with a hammer. Try the sight for fit, repeat until the sight will barely start under firm finger pressure, then drive it in. This will peen the dovetail edges down , tightening it. No need to punch divots in the metal.
Here's a link...
http://forum.lugerforum.com/showthre...light=dovetail
Ron