30-378 wby re chamber question

[JD250]

So I've got a 30-378 accumark that I am considering rechambering wondering if any one has ideas on where to go with this thing. Was throwing around the idea of the 338 edge or 338-378 any opinions or thoughts would be appreciated
Thanks

 

[Rich Coyle]

The bold face is too large for an Edge. Of the two you are limited to the .338-.378.

 

[JD250]

The bold face is too large for an Edge. Of the two you are limited to the .338-.378.

Is it possible to change the bolt face or do I just have to buy a new bolt?

 

[WAMBO]

If it was me I would go with the 338 Lapua, similar to the Edge, uses the bolt you have and the Lapua brass is way better.

 

[Chandalar]

300 Norma Mag.

 

[el matador]

I'd go with the 338-378. I have one and love it. The Lapua is a good option since the brass is better quality but you'll lose a few FPS to the Weatherby. You could also consider a 30-338 Lapua, or an improved version of the 338 or 30-338 Lapua. The 300 and 338 Norma mag cartridges would fit your bolt face, but with the length of your Weatherby action there's no need to go with the shorter case design.

If you're into wildcatting it would be cool to build something off the .416 Rigby case.

When my 338-378 barrel is shot out I'll probably rebarrel for the same cartridge in a 28" tube. My second choice would be the 338 Lapua Improved.

 

[JD250]

I'd go with the 338-378. I have one and love it. The Lapua is a good option since the brass is better quality but you'll lose a few FPS to the Weatherby. You could also consider a 30-338 Lapua, or an improved version of the 338 or 30-338 Lapua. The 300 and 338 Norma mag cartridges would fit your bolt face, but with the length of your Weatherby action there's no need to go with the shorter case design.

If you're into wildcatting it would be cool to build something off the .416 Rigby case.

When my 338-378 barrel is shot out I'll probably rebarrel for the same cartridge in a 28" tube. My second choice would be the 338 Lapua Improved.

Thanks for all the info I never really thought about all the lapua cartridges I'm just doing this because I can not get my current gun to shoot I've tried almost every combo of powder and bullet I can think of and nothing will shoot so I've given up and am going to try something new.
Thanks again

 

[yobuck]

I'd go with the 338-378. I have one and love it. The Lapua is a good option since the brass is better quality but you'll lose a few FPS to the Weatherby. You could also consider a 30-338 Lapua, or an improved version of the 338 or 30-338 Lapua. The 300 and 338 Norma mag cartridges would fit your bolt face, but with the length of your Weatherby action there's no need to go with the shorter case design.

If you're into wildcatting it would be cool to build something off the .416 Rigby case.

When my 338-378 barrel is shot out I'll probably rebarrel for the same cartridge in a 28" tube. My second choice would be the 338 Lapua Improved.

The Rigby might be cool, but there would be no velocity gain over the Wby case unless its an improved version.
I'm curious about the length of your current barrel? My son has a 30" on his 338x378
and were a bit sorry its not 32" as 2950 fps is about max for accuracy with a 300 gr.
My B I L gets 3050 with the standard 416 case, but thats with a 36" barrel on a Bat action, which just might make it apples and oranges.
As for the 300 Norma on a Mark v action, I have one, and find it works very well on that action.

 

[el matador]

Thanks for all the info I never really thought about all the lapua cartridges I'm just doing this because I can not get my current gun to shoot I've tried almost every combo of powder and bullet I can think of and nothing will shoot so I've given up and am going to try something new.
Thanks again

Have you bedded the stock? I can't blame you for giving up, I did the same thing with my 270 WSM. I put a Pac-Nor barrel on it and now it's a tack driver. Since you're already set up to load for the 30-378 I would consider putting a match-grade barrel on there and sticking with the same cartridge. .338s are fun though and I think they're a better use of all that powder.

@Yobuck, I'm sure the 300 Norma would work really well on a Mark V action. There's plenty of room to run Lapua brass though, so based on length alone there wouldn't be an advantage to the Norma. I realize that you can get factory brass and dies for the 300 Norma however, so that's a good reason to choose it.

One thing I've noticed about my 338-378 is that its very finicky. Not that its hard to find a load for it, but this gun will let you know if you're in the ballpark or not. Typical load development for me shows groups ranging from 3" to under 3/4". I actually like this. It makes it easy to zero in on a good load and rule out the bad ones. I've also noticed that if my rest isn't solid I will get erratic groups (mostly vertical stringing).

 

[JD250]

Have you bedded the stock? I can't blame you for giving up, I did the same thing with my 270 WSM. I put a Pac-Nor barrel on it and now it's a tack driver. Since you're already set up to load for the 30-378 I would consider putting a match-grade barrel on there and sticking with the same cartridge. .338s are fun though and I think they're a better use of all that powder.

@Yobuck, I'm sure the 300 Norma would work really well on a Mark V action. There's plenty of room to run Lapua brass though, so based on length alone there wouldn't be an advantage to the Norma. I realize that you can get factory brass and dies for the 300 Norma however, so that's a good reason to choose it.

One thing I've noticed about my 338-378 is that its very finicky. Not that its hard to find a load for it, but this gun will let you know if you're in the ballpark or not. Typical load development for me shows groups ranging from 3" to under 3/4". I actually like this. It makes it easy to zero in on a good load and rule out the bad ones. I've also noticed that if my rest isn't solid I will get erratic groups (mostly vertical stringing).

I have not bedded this rifle it's a factory weatherby accumark with a timney and it was "accurized" by gunwerks when I bought it and sent it to them to mount their g7 and cut turrets for it. It will shoot one group in the 3/4" range but when I go back to proof the load it's all over the place like 3" group with the exact same load I've just lost faith in it but I'd be willing to try anything to get it to shoot you guys could recommend before I throw in the towel...

 

[cape cove]

What loads have you tried in your 30/378. Powders, bullets primers etc

 

[Pdvdh]

Bedding the action is about the first thing I'd do, rather than the last thing.

But it's never too late to try. With all the shooting you've already done, you should know right away if bedding improves accuracy.

 

[JD250]

What loads have you tried in your 30/378. Powders, bullets primers etc

I've tried 190,210,215 bergers since I live in California I tried the ttxs's in 168 180 and 200 with no success and 210 nosler accubond I tried all these bullets with different combo's of rl25, 869, retumbo, h1000 and 50bmg... I may have forgot some but that's should give ya an idea of what I've done... oh yeah I used federal 215 primers....

 

[cape cove]

Reason I asked about the bullets is because mine does better with flat based bullets than with the boat tailed ones. The accubonds don't do well in mine, but the Partion does real good. Some boat tails such as the LRX do good in mine, but overall not so good. My go to powder is H-870, but the newer RL-33 is also great for me. What kind of groups are you getting with the 3" ones, 2 in one out or are they 5 shot groups.With My 30/378 I use 3 shot groups. My go to load is 115 grs of H-870, Fed 215 Wea case with an oal of 3.790. Another load that does good for me is the 175 LRX with 115 grs of Rl-33, Fed 215, Wea case and an oal of 3.731 Hope this might help you. These are max loads in my rifle. If you try these reduce and work up.
The 200 gr load gets just under 3200 ft/sec and the 175 LRX runs 3405 ft/sec.