would love to know the answer to this. I just finished up a low wall in 25-20ss and still trying to find a load for it, and a good mold. I have the original ideal loading tool with a good mold cavity,,, need to narrow down powders.

My experience, trying reduced loads in my own K-hornet, is that Lil-Gun likes to be up above 25k psi.   A load attempting to duplicate the .22 Magnum Rimfire velocity with a 35 grain bullet wasn't successful at all.   Quickload says that load is around 13k psi.   Loaded up to full power with a 40 grain Sierra it is magic.   But that's a 35k psi load.  Gun was a 14" barreled Contender.  

Lil-Gun will be way too slow even for a 1500 fps load in the .25-20.  Pressures will be even lower than my reduced load.

I also use #9 in the .25-20 and .25-21.   An interesting alternative is Blue Dot.   About the same speed.   I have yet to really wring it out.  I have wrung out 2400, but didn't get the velocity variance or the accuracy of #9.