Gerald, Here's something I found in the Lyman Ideal Hand Book
#39. On page 129 it references AL-6 specifically for magnum
loads. On page 130 it lists two 10ga & two 12ga loads
10 ga
1 5/8OZ & 38.0 GR
1 7/8OZ & 37.0 GR

12 ga
1 3/8OZ & 32.0 GR
1 1/2OZ & 30.0 GR

Copyright May, 1953.

Hope this helps, Chris