oh el dee
I have tried this and it does work. The real hard part is shaving the shoulder and the tip of the key down just enough. Too much and you fuct it. Too little and you won't get the right bounce back witch pops up the tumblers.
Also, you have to have the right key to start with. So you have to either carry around a bunch of pre-cut keys that you have tested and a tomohawk (the little mallet that you hit the key with), or you have to find out what the make and model of the lock you want to bump is and then go get a key cut for that then trim the shoulders and the tip.
And timing is a biatch. To fast and it won't werk. To slow and it won't work.
I'll stick with an old credit card for now, and in the case of dead bolts I'll use my rake.