When I first loaded my 264WM, the data was from when the 264WM was new. So I used a chrony to achieve the 3200fps with a 140. ( I got 3150) . The 264WM was designed around the 140, BTW. The 6.5m 140 is a bit of ballistic magic. After trying H-1000, RL25, N560, Magpro, Retumbo, , I found the accuracy and velocity with Magnum. Winchester 264WM came from the factory with a short throat making it quirky to reload . My gunsmith throated it normal, so I had few problems Before these new slow powders, IMR7828 was an often recommended powder, but don't expect the 3200 !