RL26 seems to be the magic sauce! That’s a pretty stiff load for a 156… I’d be hard pressed to get the bullet seated and would be super compacted. I also use a 12” drop tube.
I’ve got a 20” tikka @ 2900 with a 130 AR Hybrid, and a 22” Lilja @ 2930 with a 147ELD. Reloader 23 and 26 give similar speeds. I’m in the 51-53gr range.