[JDL]

Use the proper terminal. Using to large of wire can lead to failure, will it work in a pinch, yes, good habit to get into no.

As to the current ratings on crimp it's more of a gray area then black and white. Quality terms are tested to a particular UL standard. and blah, blah they test that the proper connector will run cooler then the conductor at the rating of the conductor.

There are limitations but for our FRC purposes the proper crimp for the conductor will handle the load, ie a yellow ring on a #12 will handle 40 amps.