.338-378 Powder and COL

[builtbybama16]

First let me say I am just getting into reloading. I would like to begin experimenting with loads for my Wby Mark V Apex .338-378. I would ideally like to be able to load either Hammer Hunter 282 gr or Barnes LRX 280gr. I am open to other bullets and weights but I am trying to stick with something that I don’t have to worry about structural integrity at closer ranges if opportunity presents itself. From what I have read those two seem to be the best candidates at a heavier projectile weight. As I don’t want to damage my rifle or myself, that leads me into powder selection and COL.

First, does anyone have any first hand experience using USP 869, N165, or H4831? I chose those because they are available. I looked at Barnes load data and they only had up to 250gr and Hammer didn’t have any load data on their newest load data sheet for that caliber. They just mentioned that their bullets aren’t sensitive to seating depth. I understand precision is the name of the game in reloading. That said, it sounds like it would make loading with Hammers less complicated in a way. It would seem you would just need to determine a safe powder load and COL. Am I wrong in thinking that?

Second, I see COLs all over the board. Some much lighter projectiles have a shorter COL than some of the heavier ones. I don’t quite understand how the projectile can be seated deep enough to make a lighter projectile with the same diameter protrude farther. It just seems like it’s not an Apples to apples comparison. Can someone please elaborate on what a good guide for COL should be?

Thank you!

 

[rustywpayne]

Of the powders listed US 869 will typically generate the most velocity but can be fickle with temperature variations. I shoot US 869 in a 30-378 and would expect a maximum charge 10 +/- grains lower for heavy projectiles in the 338. I have not experimented with N165 but have utilized N170 in the 30. Other available options for powders are 20N29, 24N41 and H50BMG which work well in the 30 version.

 

[builtbybama16]

Thanks for the input! I have been doing a lot of research and looking for forgiving loads. Just isn’t a ton out there for that particular cartridge.

 

[InkedElkSlayer]

A few comparisons…

Barnes usually prefer a little more jump compared to Bergers, etc. I have shot them in numerous calibers. Start at 15 thousandths off the lands and work in, in increments of 10 thousandths. That would equate to a longer COAL on the first group and get progressively shorter each group.

I shot Reloader 25 and H1000 out of a big Lazzeroni for years. I shoot H4831 in several calibers, but never tried it in the Lazzeroni. So I’m no direct help on that.

I have a Redding Deluxe 3-die set of dies with no 338-378 to go with them. I would off load them if you need dies.

 

[hdc77]

Hi, I’ve used Hammers extensively and the Nosler load data is the best starting point I’ve found. If I may suggest, and you may know this already, pick a slow burning powder that gives you around 95% or more case fill abounding compression . In terms of seating depth, Weatherby rifles are notorious for having a significant amount of free bore, if you can, measure your distance to the lands, and likely load at magazine length.

 

[builtbybama16]

Hi, I’ve used Hammers extensively and the Nosler load data is the best starting point I’ve found. If I may suggest, and you may know this already, pick a slow burning powder that gives you around 95% or more case fill abounding compression . In terms of seating depth, Weatherby rifles are notorious for having a significant amount of free bore, if you can, measure your distance to the lands, and likely load at magazine length.

Thanks! I really appreciate the input. I was leaning toward beginning with N165 because of availability. I would like the H1000 but I cannot find it ANYWHERE!

 

[hdc77]

H1000 is dropping here and there, Hodgdon had it on Monday. Good luck.

 

[hdc77]

Thanks! I really appreciate the input. I was leaning toward beginning with N165 because of availability. I would like the H1000 but I cannot find it ANYWHERE!

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[MillenialHunter]

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There’s some H1000 available if you are still looking.

 

[EsotericJunkie]

You might want to try a stiff load of Retumbo if you can find any.

EJ

 

[jonmt]

I have used us 869 in the 30-378. I know its not the 338 but case capacity should be close.

With 196 hammer hunter i am getting 3330 and .25 moa.
Us 869 is cheaper and easy to get.
Probably one of the easiest loads I have ever tried.
Was shooting 200 grain accubonds at .5 moa.