I took mine to the range yesterday for the first time, and tried 54.0 grains of H4350 and 220 grain Barnes Originals. Very accurate. I'll be trying cast bullets soon.
On the subject of 348 Win. loads and having a Win/Brng Mod. 71 built a Ruger NO.1 in 348 as well. Other than barrel, altered forearm, used different extractor and have not had the time to shoot only test fire couple times to check for function but with more time now am taking to range next week to see just how it does. I definitely like the caliber and figure it will work very well on about anything in my area.