Daryl,
Thanks very much for the info, currently loading up some slugs with AP-100 (similar to but not the same as SR 4756), will try them out over the next few weekends.
Had some interesting chronograph data last weekend...
Tried some AP-70N (Universal Clays), the load was an ACTIV case, CCI 209 primer, a Gualandi 24 gram wad with the petals removed and a CBE 680 grn HP Paradox style projectile and roll crimped. The velocity registered over my CED Millenium 2 chronograph was 1450 fps, I thought this was too high and the wad column might have been casting shadows or something over the screens, but I also put a few over a mates Oehler 33, same velocity. It certainly gets your attention off the bench, as the GP only weighs a shade under 9 lb.
I have the 1st, 2nd and 3rd editions of the Lyman book as well, they certainly did have some fun making up all the different loads in the books. Regretably we can't get Longshot powder over here, I asked ADI about it, it's not sold under another name here either, AP-100 is the slowest of the "shotgun type" powders they have available, must say I was very impressed with the help I received from ADI, as they sent through quite a list of load data including velocities and pressures for slug loads using AP-100, which is not listed in their book.
Will let you know how these loads go, should have some brass cases from RMC coming soon too.