I worked with mine extensively and systematically with five powders and mainly two gaschecked cast bullets before finally realizing it REALLY needed a bedding job. I was stuck on it, almost gave up but liked the gun and had already paid to smith the trigger right out of the box so started playing with shims under the action and it started to tease me. I always shot and measured 5 shot groups at 100yds with 6X scope extra heavy reticle and EJS? fore-end stabilizer on big 300yd benchrest bulls! So 600 rounds later with mostly 2 bullets with H110, W296, H2400, IMR4198, IMR4227. Even some jacketed stuff wouldn't shoot so I took it to the smith as a last ditch effort and he bedded it really solidly and that fixed it completely; he could tell it was moving around, and that was a new gun. Live and learn, didn't test it much after that, just went with:
all bullets quite heavily crimped:
20.3gr H110 CCI350 210gr mold plus gascheck (which fit mag nice) is my regular plinking load which was quite consistently benching 5 shot groups at 3" (not without exception) but not uncommonly putting 4 at less than 2" centre to centre
I don't use a chrono but did chrono one of these at 1751fps.
looks like I also had good luck with above bullet with 19.0gr IMR4227 CCI 350
21.3gr H110 with 240gr XTP HP work well too
looks like I also had good luck with 19.5gr H110 240gr XTP HP
worked with one box of 265gr FP and optimized H110 at 21.0gr; this load had 4 shots in 1 and7/8" (just under 2") without fore-end stabilizer