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338-378 accumark

338-378 accumark
« on: February 01, 2019, 11:22:00 AM »
New to the forum. New to weatherby rifles.
Saved up lots of coins. Bought a weatherby 338-378 accumark.
Warne 20moa base
Leupold 8.5-25x50 LRP

Broke in the bore according to the weatherby instructions.
Started working handloads

Will not group. I am a serious reloader and shooter. My 7mm rem mag, 300 win mag, 308 win and 257 weatherby all shoot MOA or below.
This thing looks like a shot gun pattern. Please help.

270 grain Hornady Eldx over retumbo

270 grain hornady ELDX over h1000


Tried the 270 grain over magpro (which I use in the other 3 magnums)

3” at 100. Off atlas bipod and rear bag and concrete table.

The 285 hornady eld-match and h1000 will get close to 1”.


Called weatherby. Not much support. Said they would call me back March 1

Any help appreciated.

Grouchy

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Re: 338-378 accumark
« Reply #1 on: February 01, 2019, 12:51:34 PM »
I'd try a few more different weight bullets. The scope and bases are still tight?  Welcome to the nation!  :)

Blackbear3

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Re: 338-378 accumark
« Reply #2 on: February 01, 2019, 01:17:50 PM »
Welcome to the Nation!!! Several members are 338-378 fans and will be more help, Weatherby is moving and customer service has been a little slow lately. You might want to play with COL with the loads close to an 1".
We stand for the Flag, and we kneel for the fallen!!!

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ctw

Re: 338-378 accumark
« Reply #3 on: February 01, 2019, 01:39:11 PM »
  There may be a simple solution to get those hornadys to group, or your rifle just won't shoot them no matter what you try. As grouchy has told you; you might have to try other bullets such as nosler or sierra. I know one thing for sure; and that is you're going to have to use a vld seating stem while seating the eld-x or the eld-m bullets. Hornady sells one and recommends that you use it. If the seater stem is leaving a ring on the ogive of the bullet, that would make for erratic bullet behavior. Rather than contacting weatherby over this issue, you might want to give hornady a call or at least go to their web sight and see if you can obtain a solution.  ctw

Re: 338-378 accumark
« Reply #4 on: February 01, 2019, 01:55:24 PM »
Thank You all for welcoming me! And thanks for the advice. I did buy seating stem for the eldx for my 300 win mag now that you mention it.
Just to answer a few questions.
I did check the torque on base, rings, ring caps, and stock screws.
I actually loosened the stock “action screws” and re torqued them according to weatherbys page.

I contacted hornady. They ran the bullet lot numbers and said those bullets tested 0.70” at 200 yards.

So I have honestly tried to help my own cause a little.
I did order some hornady 230 eldx
And some Barnes ttsx

I will keep working till I get this right. This is a beautiful gun and I had to turn loose of a vintage Remington 700BDL Safari Grade in 375H&H to be able to make this dream come true.
But with the groups it’s more like a nightmare right now.

Thank You again for the advice.

I can’t find a modified case so I plan to drill and tap one of my own cases and see where the lands actually are.

Blackbear,
Not sure I understand the 1” about the col.

Do you mean it may need to be 1” longer than recommended COL

224KING

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Re: 338-378 accumark
« Reply #5 on: February 01, 2019, 07:11:11 PM »
BlackBear means for you to play with the overall cartridge length on your load that shoots the best.might shorten or lengthen just a bit to see if you can tighten up the group.
Sorry... Yesterday was the last and final day for any and all complaints whatsoever.

I try to avoid temptation unless I can't resist it.

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Re: 338-378 accumark
« Reply #6 on: February 02, 2019, 08:56:37 AM »
Do you gentleman typically put any crimp on these 338-378?

I do not crimp anything else but wondered if maybe I should?

The groups I have been shooting trying to find what it likes were all single fed into the mag box with time between shots for the barrel to cool.

Just pretty concerned I may not find a load of anything it likes.

224KING

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Re: 338-378 accumark
« Reply #7 on: February 02, 2019, 09:31:46 AM »
What kind of group do you get if you shoot 3 rounds as fast as you can?This type of group is how I rate the accuracy of a rifle and a particular load.
Sorry... Yesterday was the last and final day for any and all complaints whatsoever.

I try to avoid temptation unless I can't resist it.

Everyone has a photographic memory.Some just don't have film.

Re: 338-378 accumark
« Reply #8 on: February 02, 2019, 09:39:04 AM »
2.5” all the way to 4.5”
That’s with the 270gr Hornady ELDX over retumbo, starting load through 1.5 grain below max. At that point the bolt handle became sticky.
That’s bullets seated according to loading data.

I have only tried those and the 270 grain eldx.
And 285gr Hornady eldmatch

That’s cause what I shoot in other rifles.

I have some Barnes ttsx 225 grain,
Barnes 250 LRX and hornady 230 grain on order.
As well as h-1000.

I did try the h-1000 and 270’s on the bottom half of powder scale.

Did not do any better.
Waiting on

Re: 338-378 accumark
« Reply #9 on: February 02, 2019, 09:41:37 AM »
Also someone mentioned the seating stem marking the bullets on the ogives.

I looked there is a very very faint fine line where the seating stem is contacting the bullet

Grouchy

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Re: 338-378 accumark
« Reply #10 on: February 02, 2019, 03:07:17 PM »
Do you gentleman typically put any crimp on these 338-378?

I do not crimp anything else but wondered if maybe I should?

The groups I have been shooting trying to find what it likes were all single fed into the mag box with time between shots for the barrel to cool.

Just pretty concerned I may not find a load of anything it likes.
I crimp most of my loads with a Lee factory die, if available. The exception right now is my 338 Lapua Magnum as it is a single shot. I had a rifle that took a long time to find the exact load it liked after trying 5 different weight bullets and several powders. it was worth the effort!   :)

Blackbear3

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Re: 338-378 accumark
« Reply #11 on: February 02, 2019, 04:07:37 PM »
BlackBear means for you to play with the overall cartridge length on your load that shoots the best.might shorten or lengthen just a bit to see if you can tighten up the group.

Thanks, that's exactly what I meant. Busy with an ice fishing contest the last 24 hours, outsmarted by the fish again. At least the temperature swung from -30 to +38!!
We stand for the Flag, and we kneel for the fallen!!!

Doug-NRA Life Member

Re: 338-378 accumark
« Reply #12 on: February 03, 2019, 07:25:04 AM »
I'll help you out the best I can.  I have one of the first Accumarks in .338-378 and absolutely love it and am sure you'll love your's once you find the load it likes.  Let me start by asking you is there a particular reason you want to load the 270 grain Hornady ELDX bullets?  What are you planing to do with your rifle, target shoot, hunt, or both?  Are you certain that the scope you're using doesn't have any problems?  Even brand new scopes can come messed up right from the factory.  What factory loads were you shooting out of the rifle and how did they group for you?   

In my rifle I load 200 grain Nosler Accubonds and 200 grain Combined Technologies Ballistic Silver Tips and they shoot sub-MOA, 3/4" or better at 100 yards.  I'm lucky in that they have the same point of impact out of my rifle and I use the same load for both bullets.  Nosler makes the AccuBond Long Range bullets in 265 and 300 grains which would be along the lines of the Hornady ELDX bullets.  I would try different bullets and different bullet weights as it could simply be your rifle doesn't like 270 grain bullets.  I've had lots of good luck with Hornday and Nosler bullets over the years but that's not to say a particular rifle isn't going to not like them.  I don't know off hand if Hornady lists loads for Viht N165 powder but if they do I'd give that powder a try with the 270 grain ELDX bullets.  If they don't I'd try the Nosler 200 or 250 grain AccuBonds or the 265 or 300 grain AccuBond Long Range to see if they shoot any better.  Another option is to load the same bullet and weight and see how they group with your reloads compared to factory loads.  Some rifles are very picky about what loads they like so this can take some time to figure out.  One other thing I would do is give the rifle a very good cleaning before you switch to a different load during your accuracy testing. 
« Last Edit: February 03, 2019, 07:28:37 AM by Chris338378 »
Nothing is better than a Weatherby, big bore magnum, or a Colt.

Re: 338-378 accumark
« Reply #13 on: February 06, 2019, 09:05:45 AM »
Thank you all very much.
Let me start to answer these to the best if my ability:

I did NOT try any factory loads to start. I immediately had sticker shock at the price of the factory Ammo, and figuring I would load for it anyway, went straight to handloads versus factory. I loaded 40 rounds at start charge to use to break in the barrel and fire form the brass.

I primarily want to develop one load per rifle that I can use as a hunting round and also to practice shooting longer ranges. I shoot my 300 win and 7mm to 600 yards currently cause that’s the furthest I can get off my back deck at my farm.

I do not wish to have certain loads for certain things. I would like a round that I would feel comfortable shooting a game animal at distances of 800-1000 if the conditions were favorable, I was comfortable with the shot and had practiced and distances well beyond that.
I have access to a area to shoot 1200-1600 yards. I would like to develop a load to practice those distances effectively so when the time comes, I could shoot confidently to 1000

I chose the Hornady 270 grain cause it seemed like a higher BC bullet that would carry the energy well to 1000 and split the middle on the weight/energy/velocity of the 225-230 class and the 300 class of bullets

I have since ordered some Hornady 230
Some Barnes ttsx225 and some Barnes LRX 250
Some reloader25 powder.

I have no issue playing with different load charges and bullets till I find what it likes.
I also did clean the bore between each 3 shot test group and most definitely between different powders.
Also I am waiting patiently on some factory weatherby 225 grain Barnes to arrive as a basis of comparison.

Blackbear3

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Re: 338-378 accumark
« Reply #14 on: February 06, 2019, 02:36:20 PM »
My 340 Weatherby Arroyo loves the factory 225 ttsx ammo, hopefully your 338-378 does to. Keep us updated on what you find out with the other loads.
We stand for the Flag, and we kneel for the fallen!!!

Doug-NRA Life Member