I think it was you who posted "don't forget to try H4831" on the 260 load thread in the reloading forum.
That was good advice at least for mine. 48 grains and a 123 Scenar shoots like a dream in that rifle.
Yes, after fiddling with H4350, I finally went to H4831sc and hey-presto, got bugholes with 120's. Neat round the 260.