Well, the reply from Hodgdon was very unsatisfying.

Basically said all is normal, move on.

I think I am going to stick with my old dinosaur powder (IMR 4831)....at least it is linear and predictable!

Doesn't hurt that I have about 15 pounds of it!

Maybe I will try the 7977 in the 450-400....

Wanted to add the velocities from the 121 and 122gr loads:

115gr 2,164
116gr 2,149
117gr 2,159
118gr 2,156
119gr 2,172
120gr 2,176
121gr 2,204
122gr 2,216

At least the last two showed velocity increases!

I did also chronograph 6 incrementally heavier charges of 7977 in my Ruger No. 1 450/400 with a 400gr bullet. In this case, the velocity increased with every grain of powder.

The 5 one-grain increments in the 450/400 yielded velocity increases as follows:

32 fps
27 fps
50 fps
14 fps
23 fps

Final velocity with the 400gr was 2,266 fps and the load was compressed for the final 2 loads.

Just another data point, albeit with a different cartridge.

Tim