Due to the harmonics in a rifle barrel, it will have at least a couple sweet spots, a lower sweet spot and a higher sweet spot. I have never used such a low load as 25 gr, but each to his own. The .45 Colt used 40 grains when it came out as a comparison.
I shoot a real Hawken, not one of the contemporary guns, but typically, there will be an accurate load around 55 to 65 grains and then another in the 90 or so range. You just have to take it out and shoot a couple hundred rounds and see what the barrel likes. This is common, a low and a high sweet spot with an inbetween that wont hit anything.
Like I say, I shoot a real Hawken and my upper sweet spot is 120 gr. That is the load I use for hunting. The rifle also has an accurate load at about 70 grains. That is what I use at rondys to take the pilgrims plunder.
My Favorite .53 Cal Hawken--32" Barrel--I built it in 1985. It is one of 4, with 2 other .54's and a .50.