Depending on the derailleur, how you route the cable around the fixing bolt can affect it's range. One wouldn't think that going to the left or right of the bolt would make a difference, but it can. Check the manufacturer's instructions for the specific derailleur you have and make sure you have the cable routed correctly.

Other than that, I would suggest adjustments to the limit screws or straightening the derailleur hanger, but it sounds like you've already addressed both of those.