Howdy, wonder if anyone has used the H380 loads as shown in Seirra's manual, for their 75gr HP bullet , in .257 wby mag?

I have these bullets left over, and the gun & caliber is brand new to me.
Seems everyone shoots a bullet weight/type I dont have yet, and I want light and fast anyway, lol. "long range Coyote"

thanks

That powder in that cartridge should create a flash about 4 feet in diameter.
I would pick an extruded powder.

lol, yea thats kinda scary

So far I am using the "standard" powders of RL22 and H4831. Though actually H4831SC.

Have not shot it yet (it is a Howa-Bee S2).

Use H380 in the .257 Weatherby at your own risk. Ken Waters' Pet Loads report on the cartridge recounted how the use of H380 and 87-90 grain bullets at moderate-level published load data (Sierra and Lyman) actually froze the bolt on his MkV rifle. His loads showed much higher-than-expected pressures, and he strongly recommended against using this powder in the .257WM.

OTOH this is just a single instance - but if I was to try H380 I'd start at the lowest starting load I could find. Since I have so many other powders which are better suited to the big .25's case I'll eschew the use of H380.



.