I loaded some 300's to shoot in my new Vanguard in 300 WBY, my buddy wanted some ammo for his AccuMark too. The load I used was a Rem case, Fed 215 primer, Nosler 150gr BT, and 67grs of AA-4064. I was very pleased with it, felt like shooting a 30-06, and accuracy in my Vanguard was just under 1 MOA, looked like it might do better, but we had wind gust's to 30mph. The AccuMark could only do about 1.25 MOA with the same load. The only factory load I had were some Federal Vital-Shock 180's, they would do no better than 2"

I am taking a different path to a "lighter" load in my Howaby Vanguard 300 WBY.
I have a box of Sierra 200gr ProHunter BT's from the ill-fated M1917 project. I think I'll try a light load using this bullet and some RL-25 in the Howaby.

Can't try it now. My expensive WBY brass is all loaded up and the tripod for my chrono died a painful death.

ZM

My all around load is going to use some 190gr Hornady's I have, will use H-450 or AA-4350 as I have a large quantity.