Well, Ive cracked nuts as well, but probably the worst example was my first deployment to Iraq. I had a two-by-four bed frame in my hooch and I had a few large nails for hanging my gear with. I used the handle of my Mad Dog PATAK to pound them in as I was too lazy to find a hammer. Worked fine and Mad Dogs handles are tougher than nails
literally. Ive see a grizzled old NCO tap on the butt of his knife (I think it was a Ka Bar) to pierce around the edge of a tin coffee can (good reason I started carrying a P38).
I am a big believer in using the right tool for the job, but you know as well as I Stanley that some situations pop up and you have to improvise with what you have. I will add that using your knife as a hammer, pry bar, pick or chisel is a good way to damage it regardless if its built to handle tough tasks.
ROCK6