If you do end up with Alliant propellants, whether it's RL19 or RL22, bear in mind Alliant recommends NOT using magnum primers unless they specify them. They don't for the 338 Win Mag. I found Federal 210M's gave about 10fps higher velocity than 215M's, and better extreme spreads, standard deviation and accuracy.
Since you mentioned it while I was in the middle of working up .338 loads, I decided to test the proposition.
My previous best light-bullet load was a 200-gr. Ballistic Tip over 65.0 gr. of RL-15, with a CCI 250 (magnum) primer. About 2950 fps and usually about 1". In my rifle this bullet must be seated well out to get to .030" from the lands, but it has a .375 H&H length magazine so no problem.
I shot all those up -- for the next batch I tried a different lot of RL-15 and Federal 210M (standard match) primers. At 63.0 gr. the 3-shot group was huge, 4"+. At 64.0 it tightened up some, don't have the notes here but around 1.5 MOA. At 65.0 -- one group 0.6 MOA, other group 0.8 MOA. Average a bit over 2900 fps -- slower than before, but I figure that's probably the powder.
Out of curiosity I tried the exact same loads with Fed. 215M (magnum) primers). Got 1.5" or better with all groups, much smaller velocity spreads with all charge levels, and the last two groups were about the same as with the standard primers. Perhaps strangely, velocities were just a little lower (still over 2900 fps); but that may be day-to-day variations in light angle on the Chrony, etc. However, this will be the load for using up the rest of those bullets, for sure.
JF
