Daryl,
Thanks for the comments, I looked on the ADI website, AP 70N that I am using is the same as Hodgdons Universal Clays, ADI make a slower one for pistols called AP 100, supposed to be similar to SR 4756, but they list no data in shotshells for it at all. The Nobels 82 has a burning rate similar to +/- Herco. haven't tried Herco yet, always had brilliant results with it when I loaded OO/SG's.
Can't find much on Longshot it looks to have a burning rate between Blue Dot and 2400. ADI does not have anything similar to it listed, it might be made elsewhere, or at least not available to us in Australia.
I'll keep playing and see what I come up with.

Regards,
David.