I have two FA's in .475, one a custom cut 5 3/4" and the other a 4 3/4". I agree with GlennS you can't go wrong with WLP and use it for most of my light to medium loadings. But when I get into powders of the Win 296 category and want to push my bullet a little faster I use a large pistol mag primer like Federal 155.
Here are my findings:
A. 5 3/4" barrel 15.0 gr HS6, CPB 410gr WFNGC, WLP = 1104 fps spread of 13fps.
B. 4 3/4" barrel 15.0 gr HS6, CPB 410gr WFNGC, WLP = 1091 fps and spread of 21 fps.
C. 4 3/4" and 24.0 gr of Win 296, 400gr LFNGC, Fed mag primer = 1100 fps, spread of 16fps.
I find these loadings great for hunting just about anything.
Hope this is helpful.