My .300 is a .300RUM so is a different animal.
My “Economy” load isn’t exactly a “plinking” load.
In 2006, I bought 16lbs of WC-860 pull-down from .50BMG loads for $80.00.
(About what a single pound of Reloader25 sells for now !!!)
It’s analogous to the old H870 surplus powder and works splendid in the .300RUM.
I worked up to 108gr for 3,350fps with some Remington 180gr Corlokts I bought for $5/100. I bought 1,000… I cut back to 105.0gr as it is more accurate at 3,250fps. I’ve taken a couple of deer with it and it’s not as destructive as you would think.
Closer to the .300WM, I acquired a .375Ruger. Brass was hard to source at the moment. I found that I could form a “useable” case by running the .300WM through the .375R die to expand the case neck. I expanded them with a 10gr load of Bullseye and a wads of tissue paper. Later I flared the neck with a Lee Universal expander and seated a Lee 255gr cast .377” bullet over 10.0gr of Unique. This gives about 1,100fps and is a marvelous plinking load. Much better than a .375” round ball over 5-7gr of Bullseye.
The Lyman Cast Bullet Manual has a number of reduced cast bullet loads using various cast bullets and pistol powders.