I put a bit of dirt into the open slide of my CZ-97B once, making sure it got in the mag. (Not blocking the barrel, mind you.)
I did get one failure to feed, but sand in a magazine will do that. Cleaned it out with gunscrubber, and the pistolw as good as new. Still runs like a champ 1000 rounds later.
Some dude at CZ Forums said I was insane and that the pistol would never be as accurate or reliable again. I guess his CZs are made out of copper, or something equally soft. Perhaps clay? *shrug*
I have in mind a "battlefield service" test for a weapon.
What you do is set up two targets, side-by-side, fifty meters apart or so. You low-crawl along the firing line, which would be set up with sand, mud, water, you name it; the same things a soldier is expected to crawl through. You crawl to one end, fire a magazine, and reload. Then you crawl to the other end, fire a magazine, and reload. Repeat until your load of magazines is expended.
Obviously, not for everybody, but probably a colorful way to test your weapon, your load bearing gear, and yourself all at once. No, I haven't done it, for lack of a the proper facilities. I think it'd be fun (on a nice day).