So I finally got out to shoot the 338, and the RL16 did pretty well. I loaded 6 sets of 3, from 67.0 grains up to 69.5 grains. With the max load I got an average velocity of 2,780. That's with the chronograph at 15 feet, so muzzle velocity must be right at 2800 fps. However, that load gave me a bad group, whereas the previous two groups were just a hair over an inch, and that's good enough for an elk rifle in my mind. 68.5 grains gave me 2,749 and 69.0 grains was 2,769. Extreme spread on one was 26 and the other 27. The 69.5 grain charge gave me an extreme spread of 50. I'll be loading up some more, probably at 68.5 grains, with different seating depths and maybe a different primer to see if I can find the magic combination.
