Usually if grips are a "tad" loose then it comes from repeated removals and reinstalations. Normally it is the hole on either side of the base of the grip that the grip pin fits in. When that is enlarged in the wood the grips tend to move slightly. You can fill it and have it be near perfect with a bit of acraglas or similar product. Be sure to use a lot of release agent on the grip pin and surounding area.