I work in quality, not for a choke company. But in my opinion for a supplier to produce a choke that is affordable....... i really don't think .003 is a bad range. I am serious when i state this if you are using calipers or telescoping gages have you checked to make sure they aren't .002 out of calibration? Just a thought.
But i also believe if there is a tolerance for these chokes unless it's an industry standard it should be printed on the package or advertised.
Anyway, until this year i always shot a gobblin thunder. Now that i am caught up in this hevi 13 maybe i will find out .003 diameter on the choke makes a big difference.