I'm not going to defend FPE breakers, but I think this needs to be said.
Purposely grounding a circuit to test a breaker's functionality is not only an invalid test, it's extremely dangerous!
I'll be that if you take any given breaker and do that, some will trip, some will not. The amount of resistance to ground that takes place in your "touch test" will vary greatly and although it may vaporize the end of the wire, it may not be enough actual current to trip the breaker (unless it was GFCI or AFCI).
Many people are shocked when they discover I am not a good electrician...