I used one a lot for about a decade, sold it 3-4 years ago.
For 250 grainers it's easy. Just keep adding any of the 4350s until the chronograph reads 2800 ft./s. That should be in the 74 grain range.
I didn't use the 250s for long though as after a couple years I went to the 225 TSX. It shot much flatter and penetrated just as well. For it I used Ramshot Big Game at just over 2900 fps.
I also used the 158 grain jacketed hollow points at about 1400 ft./s as just a great big 22 Long rifle for chicken in the bush. Somehow a 225 grainer at 2900 ft./s seems excessive on a grouse.
. For that I used Unique.
I should still have my hand loading records. Send me a PM with your cell number and I will text you my records. If you blow your ass up of course it's your fault.