I have a little trouble getting the S&W file reaching all areas in the Colt hand slot. I prefer the Brownell's Colt Single Action Hand Slot Stoning Kit. It consists of three stones of differing shapes. I can't always get all three into the slot(due to differing tolerances), but the thin wedge shaped one always works, and what a difference it makes in smoothing out the action. Added benefit to doing this is I get almost no hand spring issues after cleaning up that slot which is usually one of the roughest areas in the frame. I've used it on many cartridge and cap & ball single action pistols. It costs more--not sure current price--than the one S&W file but I've had my kit for over 20 years and have done at least 40 pistols, both my own and for friends. Well worth the time and money if you plan on using it more than a few times.