H414 (AKA W760) is a great powder, and is one I have burned a lot of over the years. In my 303 P14, it is my go-to powder for 180 grain and heavier bullets. With the Sierra 180 SFB, I get good velocities and moa accuracy, the 200 Redgwell Mk9 also is a winner with H414. It is true that it displays some temp sensitivity, but unless you are shooting targets, it is a non-issue in most hunting situations. For example, in my P14, the H414 load with the Sierra 180 is 2" lower at 300 yards when it is -20ºC than when it is +18ºC That is not a lot to get stressed about, IMHO. I quit using Varget after experiencing lot-to lot variances that I felt were excessive. H4831 is considerably slower and will not work well in the 303 Brit, if you are looking for any velocity. Your 8mm Mauser should love this powder. It's a tad quick for the 338, but will work fine for bullets up to 210 grains. The 243 will be fine also with it. If you are making a choice between 4350 and H414/760, it boils down to which shoots the best. As has been mentioned, Magnum primers usually work best with sperical powders. Regards, Eagleye.