600 to 800 fps is my range for plinking, As an autoloader must have sufficient recoil to work, you are limited in options. Longshot is for heavy loads, but you can load it down to 1000 fps. Go here for load data from the manufacture. https://www.hodgdonreloading.com/reloading-data-center?rdc=true&type=53
Stick with published data.
Universal does look like a good one That data is also on the above web page.
I use a lot of Unique it is the most flexible powder I know of. There are 10mm loads listed in the 5gr. range that look like fun. You can find these on the Alliant web page.