The 25-25 is a very small cartridge and is more suited to a faster powder, 4350 is even too slow for the 25-35, a much larger cartridge. The 25-25 might even be too slow for the 85gr NBT to open. There is a 85/86gr flatnose jacketed bullet that would be much more suited to the small cartridge. There are also bulk lubed cast lead from Meister bullets in 85grains that are very easy on the old rifles barrel, I use them for small game in my various 25's. The old 25-25 was never more than a small game cartridge
If the old Hollenbeck is in good original condition you would be much better off finding a used German drilling and using it. You can find one for less than you would spend on a regulateable insert(to adjust POI to match the 25-25 barrel) scope and bases.
I paid $1100 for a nice drilling in 6.5x58R Sauer 16ga with claw mounts and a Hensodlt scope. It will shoot sub MOA groups to 200 meters, power is equivalent to a 25-35 Win.
