Magnum and Retumbo are the way to go if you are chasing maximum velocity with 140's.
They were not around when I was working with my previous barrel in 264. I settled for about 3050 fps with 140's and H1000.
I have some 140's on the shelf along with some Magnum and Retumbo. On the "to-do" list is finding out what they will do from my new 27 inch barrel.
