So far I can pick the easy stuff like file cabinet and tool box locks with my home made picks.
well, someones going to say it, and bedsides it's good advice:
Don't pick locks that are in use. Murfies law says that the odds are 4 times greater of you screwing up and breaking the lock your picking if the lock is in use, and even if Murfy had died at birth, it's still a really risky thing to do.
so yah, go get a lockset and mess around with that. more informative, and a hell of a lot safer.
and at the original question: master locks are, as a rule, really bad and easy to pick.