Keep shunts, buss bars, fuses and breakers as far away from a flooded battery as possible. A proper hookup will have one single solitary cable connecting the positive post and one single solitary cable connecting the negative post. Of course battery paralleling bridge wires are not counted.
The shunt's milliamp wire terminals should be soldered. The contact point to the shunt's metal should be mirror bright then a coating of NON PETROLEUM BASED sealer applied over-top. I am so fussy about shunt connections I solder the wires direct to the shunt metal.
I picked up a lab grade Manganin shunt on eBay. Before the internet here took a dump. I would love to find a 4-1/2 digit 100 mv 100-amp meter, but where? I can't even search for one. Grrrr...