Dave Hall,
I was digging in some old junk and ran across this old load that i used years ago, Being that you will be using the #1 this may not be of much help. These loads were used in an old winchester, But here goes.
400 gr.rn hard cast, 45.5 grs IMR 4895----1801FPS----37,100 PSI
This data was used in 1950 and the powder was Du pont at that time.
Don' know if this will help or not, good luck and stay safe........Joe.........
