Fire forming 300 H&H, and WBY to 458 Lott

[richbug]

I am in the process of building a 458 lott. I plan on using mostly 458 win mag brass, but wanted the option of shooting the longer case too.

I have an excess of 300 H&H, 375 H&H, and 300 WBY brass, what would be the process for blowing this out to 458 lott? I recall hearing of cornmeal and bullseye, but don't know the proportions. Do I need to anneal the cases first?

[fourarmed]

That's a big step up for the .300s. I would try the .375s first. Maybe 10 grains of BE, fill case with cornmeal and a TP wad. If it doesn't completely form it, it still might be close enough to run over the expander. Otherwise try a little more powder. If it splits, anneal the next ones.

[HollandNut]

You want this 300 basic brass back I got from you ??

Is perfect for the Lott , is what I was gonna do with it ..

PM sent ..