I've been loading for my dads 8 3/8" barreled 460, a very used revolver. Have been using Hodgdon Lil'Gun and 250gr xtp and 300gr xtp bullets. As of yet I have not been able to attain the velocitys listed on the Hodgdon website. I had a lot of trouble getting consistant velocity until I had surpassed the max loads listed, even though the average velocity stayed in the same general area.
The 250 started out around 1500fps and has topped out around 1700fps. The 300gr has stayed in the 1550 to 1600fps range. ES for the 250gr at 1700fps was 59fps for 5 shots and the 300gr at 1550 was 70fps for 5 shots. I was thinking that the cylinder gap had gotten to big, cause this gun has obviously been shot alot, but factory ammo (listed at 2200fps) clocks at 2093-2154fps for 5 shots. I'm begining to think that it maybe the powder. I'm thinkin that Lil'Gun is just to slow, will be trying some h110 here shortly.
I would be very interested in hearing what your experiences are with this behemoth of a cartridge.