Here is the trip curve for the 7277.
the minimum time to trip seems reasonable but the max time does seem high.
http://www.sensatatechnologies.com/klixon/circuit-breaker-aircraft-7277.htm#tripcurve
The 2tc's appear to have a quicker trip curve.
http://www.sensatatechnologies.com/klixon/circuit-breaker-aircraft-2tc.htm#tripcurve

just curious, has someone on the list put 200% rated current through the appropriate
30A rated wire and timed how long it takes to smoke?

....and for a hydraulic pump failure mode, is the draw only going to be 200% or a lot
more if you stop the armature?