Thanks for the replies.
I too tried 3 grains of Bullseye and it shot well. In my testing the 2.5 grain load shrank the groups but raised the trajectory. I think increasing the dwell time of the bullet in the animal increases stopping power in low power non expanding loads. The reduced noise also scares them less and they resume feeding sooner if you miss. I have hit squirrels with 1000 fps loads and they do not seem to know they are hit for awhile. The slow loads seem to knock the dickens out of them and almost always bring them down right away. I may be using too much crimp and deforming the limited bearing surface of the bullet. I know you can't have too much accuracy when you are trying to hit those hairy tailed tree rats.