I was surfing the net the other day and came across a video of a man's handgun collection. When he got to his Colt he mentioned that he was thinking about replacing the trigger because it felt grainy.
I often have moments when I start yelling at my computer. This was one of them.
"No. No! You don't have to buy a whole new trigger."
The first time I was introduced to "stones", or "Alan Stones" as the manager of my shop would call them, was when we got a brand new 1911 in the store on a trade. My manager went to shoot it and said it felt rather burred and chunky and it needed to be smoothed out.
He disappeared into the back of the store and came out with a flat Alan stone and started working the slide. He called me over and explained what he was doing and handed both the stone and the gun over to me and told me to do the slide then work on the frame.
The next few shots out of it were as smooth as butter.
Essentially, stoning is polishing. It removes metal burs that you can't see with the naked eye (and some that you can) and leaves a smooth, sleek metal that will glide instead of skip along other metal parts for a smooth, clean action.
Of course, simply shooting the gun again and again and again will produce the same results as the affect of metal rubbing against metal will be its own polishing but you are talking about a couple hundred to thousands of rounds (depending on how severe the burr happens to be). You can do the same with just fifteen minutes with a stone.
Not only do they work fabulously for slides and frames but for any part where metal meets metal.
Of course, the first diagnostic level is to make sure the firearm is clean and there is no dirt or grime causing the gritty feeling, but after it's established that the firearm is clean, either get yourself a good set of stones or contact a gun smith and ask him if he has the ability to do some stone work on whatever it is you feel is a little gritty.
Here's a good little video on the Brownell's website about stones.
And the stones themselves.