Is it AC current, where using a current transformer will probably be a better bet. A small strip toroid ( or an old small mains transformer you have cut the windings off without disturbing the core itself) with a secondary of 1 turn of thick copper wire, around 16mm, and a primary winding of 10 turns of 1mm copper wire. Simple, reliable and much lower error as well instead of destroying the shunt itself.
I use one to increase the sensitivity of a regular power meter, as I wanted it 10 times more sensitive, so used an old 35W toroidal transformer for the core, and the current sense winding now is running at 8A peak , but the internal sense coil still has up to 80A flowing in it.