8 GAUGE BRASS SHELL TURKEY LOADS

[WHO]

I have a P grade hammer gun on a 7 frame with 34" barrels and full chokes. The gun was originally shipped from Parker in 1894. It was returned in June of 1914 to have the barrels rebrowned and the action repaired and cleaned. The barrel wall thickness is as follows: .151" one inch in front of forcing cone, .069" ten inches in front of forcing cone, .062" sixteen inches from muzzle and .058" minimum wall thickness. The components I plan on using are as follows: 3 1/4" brass Rocky Mountain Cartridge, W209 primer, Alliant Blue Dot powder, .125" overpowder wad, .500" fiberwad, #4 West Coast premium magnum extra hard lead shot, .025" overshot wad held in place with Duco Cement.
I have Tom Ambrust's book but he really doesn't address loading the brass shells and using the Precision Loading components. Does anyone have any experience with using these components? Any suggestions on powder and shot quantities?