Thanks for the reply. I have Speer Manual #13, and they don't list any reduced loads for the .416 Rem. I also posted this on the big bore forum and got a response that 47 to 53 grs. of 4759 worked well with a 335 gr. cast bullet. That will give me a place to start. Accurate Arms lists data for the .416 with 5744. I may also try IMR-4227. It works well in my .338 Win. with cast bullets.

I don't ahve the latest Speer manual but it and the IMR web site might the data you need. Also the burnrate of 4227 and 4759 are similar and use simlar weight charges in reduced loads.