Originally Posted by patrickstickler
My understanding is that it's not so much a matter of taking the ammeter out of the circuit, but taking the entire shunt out of the circuit. I.e., even if you disconnected the low current ammeter wires from the shunt, you'd still be running ~400A through a shunt that is rated at 100A max, and the docs state that doing so can permanently alter the characteristics of the shunt ...
Patrick is entirely correct. I apologise for my misleading & inaccurate post.