N570 powder

[6.5x300 WBY]

.338/.378 weatherby - 285 Hammer hunters - 30" barrel - 110 grns N570 sea level = 3,100 fps. No pressure, extremely accurate @ 100 yds & 1,000 yds @ 2,200' elevation.
Only con is have to one shot, not even close to getting in mag. Like 4.106" OAL

Have you ever tried a mag fit load? My 338-378 Wby fb group says they have but IDK

 

[Mike Matteson]

I don't see 50 fps between cartridges as a large advantage. I would pick something with the most consistent brass available over going to a larger case with that small of a gain.

50fps extreme spread in the loads from one rifle would be huge I agree, 14" vertical is a killer for making long distance hits.

It's a problem with some powders being used. Especially where the temp changes greatly. I hunt in those areas where temp can change a hug amount. I had problems a great many years ago using heat sensitive powders. Even using the means of temp or 60' some powder change as much 1.7fps. So can be alot of drop if hunting in -20' weather or increased temps with less drop and go over a target.
I do realize that a lot of double based powders are able to get better velocity out those type of powders.

 

[Michael Lares]

Have you ever tried a mag fit load? My 338-378 Wby fb group says they have but IDK

I would have to go lighter bullet but so far have not found the combo I like. With my throat I'm at about .250" jump with 285 Hammer HH. With this combination I'm up against powder with the bullet which is where I like to be close to. Haven't measured how much erosion I have but pretty good round count down barrel. Doesn't matter, does very good & happy! These are a very long bullet.
Gun will shoot 325 Rocky Mountain close to same speed and still in the node but obviously works the gun a lot harder and won't out shoot / outperform these HH.

 

[Saskquatch6]

… also what's a good powder for 165 grains in 300wsm

I know this may not be all that helpful unless you were lucky/smart enough to have stocked up on RL26 when it was available, but I've found it to be the very best powder with 165/168's in 300 WSM giving 100 fps more velocity and great accuracy. Of powders on the shelf now Superformance has been the best of the rest for us.

 

[JamesWilson5]

I use super performance not best groups