Thanks for the help, its still not perfectly clear how you got the 73829 from the range but at least it works. It just has to be converted to A and remove the negative.
As I'm currently noodling using the ACS714 for current measurement, I went back to figure out why 73.829 mA was the number he gave. It ends up it's just how an ADC works.
10 bits = 1024 steps (from 0 for 0v to 1023 for full AVCC) - theoretically, mind you; there can be plenty of external reasons (read: noise) that can prevent a consistent and precise reading on the ADC pins
0.52V would approximately read as 106 in the ATmega (assuming AVCC is 5V)
4.88V would approximately read as 917, meaning that the actual range of numbers you'd read would be between 106 and 917 (or 811 steps)
Divide 60A (the range of +/-30A) by 811, you get 73.829 mA per step.
Finally, as a best practice, always oversample the ADC and average across several measurements. I've never used a single sample reliably.