geezerbiker, don't have a .445 in a rifle, but have had an inclination to build one from a .444. I can tell you, I use the load I believe your refering to. I cast a 330gr. for my DW. And use the load out of the Lyman 2nd edition, 31.5grs of 1680. It's a handful in a 10'' pistol!! Not sure if going to a slower burning powder, will get you that much. There's an optimum powder charge for every cartridge, and, you might be over the curve trying to cram that much powder in that case. Best case scenario, you might call one of the powder company's, and talk to a rep. Sometimes you can find out that they've already tried what you want to do, and it didn't work. They have alot more sophisticated equipment that we do, and are more than willing to help out. Good Luck!! gypsyman
