You'd have to find the pressure limits for your Ballard action yourself, but I've done some work on the .25-25 in my Low Wall.
Ideal 25720, 8-10 gr XMP-5744, MV 1220-1480 fps. I've gone to 12 gr and 1800 fps with nothing to show for it but inaccuracy.
Tried 4198 from 12 to 15.5 gr and no accuracy to show for it although it got to almost 2200 ft/sec with the last loading. 12.5 gr with the 87 gr Remington jacketed bullet gave a 1-1/8" group at 100 yards. Using the gas checked Ideal 257464 with the same powder charge got about 2" at 50 yd.
I went from 12 to 18 gr of Reloder 7 with the Remington JFP and the same range of charges of VihtaVouri N-133. Generally the best accuracy was in the middle of the charges (14-15 gr) going 1-1/2" at 50 yards and 2-1/2" at a hundred for the best average groups. 17 gr of VVN-133 shows some promise and the bullets just shade 2000 fps.
I don't know how much help this will be to you. What I've been trying to do is to take the .25-25 out of the .25-20 range of velocities and get maybe a Hi-Speed loading for the 87 gr bullet around what the 60-gr did in the .25-20 WCF, around 2200 ft/sec. So far though, the cartridge seems to be happiest in the 1400-1700 ft/sec range, and lower than that with cast bullets, although gas check designs seem to take a little more velocity.
In your rifle, I'd recommend sticking with the .25-20 level loadings. The 8-10 gr XMP-5744 loads showed no signs of pressure problems.
On an unrelated note, when is Jamison going to make some .25 cylindrical Basic brass for the legions of .25-21 and .25-25 enthusiasts?
I think a large part of my accuracy problems come from the variances in the Bertram brass I use.