Try JLK 108 grain VLD's jammed onto the lands over a stout load of H4831, 56-57 grains is OK in my rifle, but, work up to this charge in yours. Have consistently had sub one inch groups at 300 yards with this loading.
My testing of my lot of Viht 165 in a 22/250 AI, 224 Clark, 25/06, and 25/06 AI, shows that it is about 0.5 grains slower in burning rate than H4831sc in the 22/250 AI, and about 1.0 grain slower in the 224 Clark, 25/06, and 25/06AI.
I have listed below my chronograph details with H4831sc, and Viht N165 in my 25/06 (Sako L61R Action, Shilen 24 inch SS barrel)using Winchester cases, Remington 9.5 primer, and the Nosler 100 grain BT.
57.0 grains H4831sc - 3,172 fps
58.0 grains H4831sc - 3,232 fps (Max)
57.0 grains Viht165 - 3,205 fps
58.0 grains Viht165 - 3,255 fps
59.0 grains Vith165 - 3,342 fps (Max)
I found that when using short cut extruded powders like H4831sc and Viht165, it took about 59.5 grains to fill to the base of the neck when using Remington cases, and 60.7 grains when using Winchester cases.
So maximum loads of either powder when using a 100 grain bullet will give about 96 - 99% loading density. Hope the above helps. Regards Brian.