I dont think you want to use washers under the grip. If you do it will leave a small gap between the grip panel and the frame, this will let in more dirt lint etc and look cheap. If you have the slim grip bushings on the frame you have a couple of options.
1.Remove and replace with stock bushings.
2.Shorten the grip screw.
You can get replacement bushings from www.brownells.com and they also have a screw holding gizmo that will hold the screw secure while you grind it down. Be very careful with the grinding, dont go to fast, and watch the threads so they dont get buggered and wont go back in the bushings. Good Luck!!!
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