338-378 shooters. What powder

[6.5x300 WBY]

Just looking at what would be the best powders to look for for the 338-378.
I just picked one up and have several good powders that may be good. H1000,RETUMBO, N570, US869.
I see PV has LRT available and do you feel it's worth trying it out?

I will be shooting a variety of bullet weights. I have 267 HHT ,285 ELDM, AND have a box of nosler 265 ABLR incoming from a fellow member. I will also be playing with 220HHT too.

So basically what are your preferred powder choices for this big girl?

Thx
Brian

 

[Seabeeken]

Sounds like its time to start testing to see what the rifle says. Ive always thought that was part of the enjoyment of the hobby. Ymmv

 

[6.5x300 WBY]

Sounds like its time to start testing to see what the rifle says. Ive always thought that was part of the enjoyment of the hobby. Ymmv

Very true. But a starting point that other 338-378 shooters can help me avoid more inappropriate or not good powders. That's all.

 

[K.E.C. Darkside]

Just looking at what would be the best powders to look for for the 338-378.
I just picked one up and have several good powders that may be good. H1000,RETUMBO, N570, US869.
I see PV has LRT available and do you feel it's worth trying it out?

I will be shooting a variety of bullet weights. I have 267 HHT ,285 ELDM, AND have a box of nosler 265 ABLR incoming from a fellow member. I will also be playing with 220HHT too.

So basically what are your preferred powder choices for this big girl?

Thx
Brian

Howdy, don't have a 338.
Been playing with a 30-378, with 230hyb.
H-1000, N-570 and Retumbo.
Retumbo was the easy button and my barrel likes a mild load 101.7
At 300yds 5 shots touching, played with seating depth in 3 - 5 shot shooting.
570 gave plenty of speed, but 1moa or 3" group at 300yds.
Pick your poison.
If I can help PM me.

 

[6.5x300 WBY]

Howdy, don't have a 338.
Been playing with a 30-378, with 230hyb.
H-1000, N-570 and Retumbo.
Retumbo was the easy button and my barrel likes a mild load 101.7
At 300yds 5 shots touching, played with seating depth in 3 - 5 shot shooting.
570 gave plenty of speed, but 1moa or 3" group at 300yds.
Pick your poison.
If I can help PM me.

Thx. My FB group for 338-378 shooters also states Retumbo

 

[MagnumManiac]

I have used, with success, US869, Retumbo & H50BMG. I also used RE30, never got the chance to use RE50.
Lesser than ideal powders have been RE25, H1000 & IMR7828, they worked in my 300-416 Rigby Improved with 210g ABLR, but only just, too much air space.
Now, you know my case is not a Weatherby, but capacity is very similar and the same powders above will work very well.

Cheers.

 

[6.5x300 WBY]

I have used, with success, US869, Retumbo & H50BMG. I also used RE30, never got the chance to use RE50.
Lesser than ideal powders have been RE25, H1000 & IMR7828, they worked in my 300-416 Rigby Improved with 210g ABLR, but only just, too much air space.
Now, you know my case is not a Weatherby, but capacity is very similar and the same powders above will work very well.

Cheers.

Yup. Retumbo and US869 are my leading candidates so far.
Thx MM

 

[hemiford]

Howdy, don't have a 338.
Been playing with a 30-378, with 230hyb.
H-1000, N-570 and Retumbo.
Retumbo was the easy button and my barrel likes a mild load 101.7
At 300yds 5 shots touching, played with seating depth in 3 - 5 shot shooting.
570 gave plenty of speed, but 1moa or 3" group at 300yds.
Pick your poison.
If I can help PM me.

What might be the problem with the N570 I wonder ? Different barrel harmonics ?

 

[K.E.C. Darkside]

What might be the problem with the N570 I wonder ? Different barrel harmonics ?

For my experience with N-570 it takes more tuning. Although I got it to work great for a 300RUM and 215hyb.
If you find what it likes, the speed is great.
The 215 are at 3250 comfortably.
Harmonics always plays a roll in tuning.

 

[338weatherby]

I only used Retumbo when I had mine so nothing to compare it to. It work well so didn't mess with any other powders.

 

[6.5x300 WBY]

I only used Retumbo when I had mine so nothing to compare it to. It work well so didn't mess with any other powders.

Now thats what I like to hear.

 

[MagnumManiac]

I only used Retumbo when I had mine so nothing to compare it to. It work well so didn't mess with any other powders.

H50BMG is the stand out in all 3 variants in my wildcats. It surpassed all others with ease, not so good with lighter than 225g bullets in the 338 cal, but excellent with 265g ABLR & 300g Accubonds. US869 is a close second, but when you reach max pressure, things get touchy real quick and I had to back off on a few occasions because primers wouldn't go back in and my brass is like yours, thin webs on Norma made brass. Just a heads-up.

Cheers.

 

[MagnumManiac]

What might be the problem with the N570 I wonder ? Different barrel harmonics ?

It has been my experience with several double base powders that if any parameters within the load are not 'optimum' for the powder to burn at the correct pressure, it becomes erratic from shot to shot.
My stash of Supreme 780 is a prime example, it hates air space in the case, prefers slight compression where it burns cleanly. If you get dirty loads, this is often a sign of poor powder burn even though velocity appears good, some powders do this all the time, or only occasionally.
This is why I prefer single base extruded powders 99% of the time.

Cheers.

 

[hemiford]

It has been my experience with several double base powders that if any parameters within the load are not 'optimum' for the powder to burn at the correct pressure, it becomes erratic from shot to shot.
My stash of Supreme 780 is a prime example, it hates air space in the case, prefers slight compression where it burns cleanly. If you get dirty loads, this is often a sign of poor powder burn even though velocity appears good, some powders do this all the time, or only occasionally.
This is why I prefer single base extruded powders 99% of the time.

Cheers.

I'll buy that, less than optimum case fill percentage , in the case of N570.