Looking for suggestions concerning powders suitable for reduced loads in a .375 Wby. I'm looking to use the 235 gr. Speer in a whitetail load. I'm guessing 2400 - 2500 fps or so should be about right. I have AA & IMR 4350's, IMR 4064, H 414 and IMR 3031 (also R22 & IMR 7828 but they have to be too slow??) on hand at the moment. At what point in % load density might I run into problems??

The .375 Wby is my all-time favorite. I cut my teeth on it. I would just use low-ball .375 H&H ammo in it.

For example, if you want a 2400 to 2500 fps load with the .375/235gr Speer: Get the speer manual and find the .375 H&H load for that bullet that is 2600 fps.

Fire that .375 H&H load in your .375 Wby and you are going to drop the velocity about 125 to 150 fps, depending on the load and the rifle, of course. Accuracy has always been good for me when doing this.

The .375 Wby only comes into reason for being with the heavier bullets. Easily 200 to 250 fps faster than the .375 H&H with 300 grainers, and 250 to 300 fps faster with 350-grain bullets.

Lighter than 300 grain bullets in the .375 Wby give lesser velocity gains over the .375 H&H.

You may want to fiddle with light loads for it, but I would rather fireform .375 H&H brass with the light bullets.

This brass comes out about 2.83" long after blowing out the case body, so just a little short. I use it in another old rifle, and save the full length Wby brass for two other rifles in .375 WBY.

Thanks RIP.

I guess the answer was so freakin obvious I overlooked it.

If you are going to back down a lot, be sure and use a medium burning powder like RL-15. No sense tempting fate with a reduced slow burning load.

FWIW.