I've found one load that is outstanding in my 338 Win Mag. I've used it for hunting Elk and Caribou to critters as small as Mulies. I wish I could take credit for it myself, but I actually read about the use of this powder for 225g bullets a few years ago in one of the shooting magazines.
The loading is as follows:
Rem. cases.... CCI Mag Primers....77.5g Reloader 22.....225g Nosler Partition.....
My rifle has a 24 inch barrel with a MagnaBrake on it. The velocity of this load with a ProChrono is 2990 fps and my groups are average under .75MOA.
There it is, my pet load.

Wonder if that would work well for my 225gr X bullets??

I got similar results with my 338.
73 grains H4350, win brass, WLRM primers, and 225 grain Nosler Partitions out of M70 W/BOSS. Stock rifle w/ trigger @ 3#'s. Great groups w/ velocity of 2950 fps. I did reach over 3000 fps, but got a sticky bolt lift. This is max in my rifle.

Sounds like you guys have some great .338 Win Mag loads there.

For what it is worth, my gun just will not take those kinds of loads. About 76 grains of RL 22 behind a 225 Nosler is all it wants. Actually, I settled on 72.5 grains of H 4350 behind the 225 Nosler for a velocity of 2880 fps. This is plenty of powder for my gun and it shoots great.
It sure worked on the bull elk I shot last fall and a couple of wild pigs that got in its way.

My rifle is a Remington 700 Classic that wears a 2.5 X 8 Leupold scope.

R F

NBhunter;
The neat thing about using Reloader 22 with the 225g Nosler bullets in the 338, is it's apparently impossible to reach maximum pressure with the powder. The only reason I use the 77.5g charge is that's all the powder I could put into the case and keep the bullet from unseating itself. Pressure is still quite moderate and well below maximum. The major drawback with the barnes X bullets in my experience is the lenght : weight issue. The bullets are longer for a given weight than lead core bullets. Therefore, when seated to the same OAL as conventional lead core bullets, will take up more volume in the cartridge case. You would probably never have any kind of pressure problems with Reloader 22, but I would doubt that you could get enough powder into the case with this powder to reach satisfactory results with the 225g Barnes X. If you give it a try, I'd certainly be curious to your findings. I don't claim to know everything and this is only my opinion about the use of this powder with the solid copper bullet.

I used the 225 gr. bullets for a couple of years then went back to the 210 Nosler and the 300 gr. Woodleigh depending on what I am shooting...I use the Swift, the hornady and the BarnesX, didn't try the Nosler...My take was the 225 was neither fish nor fowl...a compromise..I just love the 210 Nosler in a 338 and the 300 gr. Woodleigh is a awsome hammer..

Big differences in chambers and barrels. My 338WM hit the velocity Alliant lists for a 77gr load of Reloader 22 with only 74 grains Reloader 22 under a 225 Hornady. The load is so accurate, I quit there.