Is there a reason for it being 130 - 170, rather then 0 - 40? Is it to make it easier to use the value in some other calculation?
Yes, there are several reasons for the change. Some of them are:
Since the new scale does not superposes with the old one, you are able to differentiate them.
The old scale increases by 10, which could overestimate the difference between two scores. The new scale increase by 1, which helps to decrease the bias when comparing scores.
Another feature that helps to decrease the bias when interpreting results is the not obvious extremes, but still with a comfortable number at the middle of the scale.