Dishwashing a glock
Hell, that's reason enough for me to go and buy one.
Seriously though. If you remove the stock from the action itself (assuming you don't have a plastic type finish) Almost anything would be fine. Brake cleaner, starter fluid (if your really looking for an oil free finish, make sure you oil it after spraying starter fluid on a gun), dishsoap/detergents, anything to cut grease and oil is fine. Ammonia to cut copper. As far as lubrication motoroil, diesel, WD-40, animal lard whatever is fine too.
Do be careful as some of these chemicals maybe rough on your stock. No matter what the material is.
Your best bet would probably your muzzleloading cleaning kit. It won't get rid of the copper (of which I think people get a bit carried away with anyway), but you'll sure have a clean and rust free gun.
My favorite cleaner on almost anything and everything is windex. If it can get rid of finger prints and smears on glass and mirrors it must be doing a good job at cleaning it. Guns, stoves, table tops. Windex is the best.
It's one of those "common sense" things.