[bitwrangler]

I would use a variable power supply, amp meter and some sacrificial fuses. Slowly turn up the voltage while watching amps on the circuit until it blows? Or simply apply the rated amps (with current controlled power supply) to verify if/when the fuse blows.

I have a multiple-fuse assortment kit that was a great (too good?) deal from AliExpress. Now I'm thinking I need to do some of those tests myself to verify their rating.