I loaded a similar load with Alliant Power Pro 2000MP. I believe I used 78 grains. As it is a dense powder, I was able to seat a barnes 400 grain solid down to the first cannelure and I still have air space because the powder shakes around in there. You're right though, those 400 grain turned brass solids look like AAA batteries they are so long. I was getting about 2,300 from my Ruger Hawkeye African which has a 22.5" barrel (I sawed the threads off and recrowned. I really like the rifle and have taken black bear and deer with it. If you want a flat shooting load, look at the woodleigh 340 grain PP. The .416 Ruger can push it out the muzzle at 2,550 and recoil is comparatively mild.
How did those CEBs feed in your rifle (you didn't mention a rifle make model)? I just know my M77 African just barely fed those FN Barnes brass solids becaus I would take the corner off one every now and then when I fed it into the chamber from the magazine.
