In my rejection above of R19 I should say that, first off, while I forget the charge I used, I need to add "the rest of the story".
This was back in 2002 and I had some of the older Barnes 185gr XLC, the ones with the blue coating. I had never used R19 but Barne's Manual listed it as highest velocity. Now, that bullet was so slick that I could not get decent speed without having to use a highly compressed load. I even had to "reseat" them a week later as the powder column was "pushing the bullet out of the case". I had previously worked this load up right at 40F. 10 days before my late season cow hunt ( late December) a storm came in and temps dropped. It was 10F when I "checked my zero" at the nearby range. My groups were about 4", so I set up my chrono and found I had lost almost 200fps. I went home, ( four miles away) pulled the bullets and the R19 was a solid "cake". I had to dig it out with a small screwdriver. I then made some workup loads ( I forget if it was 72 or 74gr H4350 I settled on) and zeroed for it. Sweet juice! Now, "It could be" that the solid cake was the issue, in conjunction with the cold. They ignited fine, no hangfires, etc.I don't know if it was an anomaly, but it "spooked me", I am a total OCD Reliability Freak, ha. This was before LEE's Factory Crimp Die ( which I use all the time now on everything) and those XLC bullets were slick as snot. I'm glad they went to the relief grooves and dropped the coating line. I used Federal 215M primers, WW cases. The only cartridge that I used R19 in, ever again, was the 240W. In two different rifles, 54gr with the 90-95 gr bullets was champ. "Maybe" the larger amount, highly compressed, caked powder column at that cold temp was the culprit. I just can't use R19 in a magnum case again...
I also had some high temp issues with R22 in a 280AI but at 20F in Namibia we used R22 & 76/180 xbt in the 300WM with no problems, but I just don't use it anymore. I tested R15 in a 35 Whelen/310 Woodleigh from load workup at 70F down to 20F and it never made a bobble, good stuff! Same with the Hodgdon Extreme line. I'm one of those "True Believer's" in light Premium bullets in Medium calibers ( 338 up) and believe they cut a bigger hole than a same weight bullet in the 300WM. I used a 180NAB at 3500fps in a 338 RUM on a big aoudad. It cut a hole like a Partition, about golf ball size, all the way through. That's another great bullet, IMO. I used the 210xbt in the 340W on Plains Game and zebra and it was just awesome. The TSX and TTSX are just so much better now, IMO. Lots of great choices in the 338 caliber. Good luck to the OP!