I also have a BLR .450, I traded it for a Marlin GBL 45/70. I really like it it and their is no load data dedicated to it. The action is strong one. The cartridge case is heavier
From what I can see it is long throated and I don't crimp so options are wide open.
I have used Speer 350's, H ftx 325's and Barnes Originals so far.There is no reason it cannot be loaded to Ruger #1 45/70 range. I am just getting started with it myself but this will be after hunting season. Stay in touch.
