HobbyKing HK-010 energy meter

These are cost effective meters made for the hobby industry. I have one of these but have found the current measurement to be inaccurate. This results in the Ah readings to also be inaccurate.
My guess is that they don’t calibrate these shunt resistors for accuracy due to the cost.
Anyone seen a shunt resistor like this before??
HobbyKing 125|690x457