On Reloading 500 S&W Magnum Page I found a 370grn cast bullet W231 (same as HP38) 10.0 grn. low power load for the S&W 500 Magnum. Im thinking a 325 grain bullet would be about 12 grains of HP38/W231 powder... Anyone have used/heard of any W231 / HP38 recipes?

I have stock of H110 which I use for full power 44 magnum loads and HP38 which I use for low power loads. I wanted to stick with the same powders for the 500 if I could.

Im using 325 grn TCBBs from pennbullets.com.

I do not load for the 500, The closest is 44 Mag. I do use a lot of HP 38 and also in 45 Colt That load that you linked to would be pretty pathetic. You could probably watch the bullet leave the barrel and fall to the ground.

You can use load data for the next higher weight bullet and gain more velocity but not the other way around which you are suggesting.

If it was me, I would use a different powder,Unique is probably the mildest load based on Lymans Manual

There are plenty of recipes.

Cartridge Loads - Hodgdon Reloading Data Center - data.hodgdon.com

__________________
Still Running Against the Wind