I burned most of a pound of 4451 through a 6mm last year trying to develop a load with 95 NBTs. I was also considering it for the 270 and 30-06. I ran into some pressure problems sooner than I thought I should have and I didn't think it went through the powder measure very well. It's more expensive too.
I went back to H4831SC and Reloder 17. YMMV
Dale
