.338-378Wby

[boomer68]

Anyone loading for this round? Just picked up a Mk V Accumark and looking for some starting load suggestions.

 

[JD338]

Nice!
That wil be a long range hammer for sure. The 300 gr AB would be a top performer for sure with a MV of 2850-2900 fps.
I'm sure OU812 will come along shortly and share his loads with you.

JD338

 

[DrMike]

It does have quite a punch--at either end! They do hammer game, though.

 

[Guy Miner]

Didn't FOTIS have one of those for a time?

Heck, he's had all the other big Weatherby cartridges! :grin:

Boomer - a local doctor here has been using one for years, primarily on elk. He's happy with it. Can't say that I know his load though.

 

[DrMike]

I've pulled the trigger on several and worked up loads for more than a few. However, I don't have any of the data any longer. I've reached a stage where I am more than willing to give the pleasure of load development for some cartridges to others.

 

[SJB358]

First off, awesome rifle! That is really a great looking rifle!

Here is some QL with the 300 AB. Let me know if this helps at all.

Cartridge : .338-378 Weath. Mag.
Bullet : .338, 300, Nosler AccuBond 54851
Useable Case Capaci: 116.670 grain H2O = 7.575 cm³
Cartridge O.A.L. L6: 3.750 inch = 95.25 mm
Barrel Length : 26.0 inch = 660.4 mm

Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 63000 psi, or 434 MPa
or a maximum loading ratio or filling of 110 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !

204 loads produced a Loading Ratio below user-defined minimum of 90%. These powders have been skipped.
Powder type Filling/Loading Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time
% Grains Gramm fps % psi psi ms
--------------------------------- -----------------------------------------------------------------
ADI AR 2218 100.2 114.7 7.44 2909 100.0 63000 15150 1.380 ! Near Maximum !
Vihtavuori N570 95.6 108.4 7.02 2859 100.0 63000 14807 1.414 ! Near Maximum !
Alliant Reloder-50 101.6 118.1 7.66 2847 99.9 63000 15002 1.445 ! Near Maximum !
Alliant Reloder 33 95.4 112.8 7.31 2843 100.0 63000 14510 1.419 ! Near Maximum !
Hodgdon H870 101.5 112.7 7.31 2831 100.0 63000 14113 1.421 ! Near Maximum !
Bofors 12,7mmRA NC1214 Lot20115087 102.4 116.5 7.55 2805 96.2 63000 15083 1.445 ! Near Maximum !
Hodgdon 50BMG 104.5 114.1 7.39 2802 95.0 63000 14724 1.403 ! Near Maximum !
Vihtavuori 20N29 106.4 123.2 7.98 2799 99.1 63000 14279 1.424 ! Near Maximum !
Vihtavuori 24N41 99.2 113.7 7.37 2795 97.7 63000 14201 1.396 ! Near Maximum !
Accurate 8700 108.4 119.4 7.74 2795 99.9 63000 13637 1.408 ! Near Maximum !
Hodgdon Retumbo 98.9 107.0 6.93 2790 100.0 63000 12699 1.413 ! Near Maximum !
Hodgdon US 869 104.1 119.3 7.73 2789 97.7 63000 14263 1.411 ! Near Maximum !
PB Clermont PCL 513/520/9520 107.7 118.4 7.67 2780 99.5 63000 13813 1.421 ! Near Maximum !
Norma MRP 2 94.9 102.1 6.61 2778 100.0 63000 12935 1.426 ! Near Maximum !
Ramshot Magnum 90.1 103.7 6.72 2776 100.0 63000 12757 1.415 ! Near Maximum !
PB Clermont PCL 517 90.4 103.8 6.73 2775 100.0 63000 12748 1.415 ! Near Maximum !
SNPE Vectan SP 13 105.9 116.4 7.54 2774 99.8 63000 13576 1.424 ! Near Maximum !
SNPE Vectan SP 12 90.3 103.6 6.72 2774 100.0 63000 12717 1.416 ! Near Maximum !
IMR 7828 92.0 96.1 6.23 2770 100.0 63000 12586 1.401 ! Near Maximum !
ADI AP 2214 91.8 102.5 6.64 2763 100.0 63000 12365 1.398 ! Near Maximum !
Hodgdon H1000 96.5 102.7 6.66 2761 100.0 63000 12333 1.398 ! Near Maximum !
Bofors RP5 NT ~approximation 92.0 100.9 6.54 2755 100.0 63000 12728 1.393 ! Near Maximum !
Winchester WXR 90.7 96.5 6.25 2749 100.0 63000 12428 1.416 ! Near Maximum !
Alliant Reloder-25 92.7 99.1 6.42 2741 100.0 63000 12018 1.420 ! Near Maximum !
Vihtavuori N170 99.8 106.2 6.88 2734 99.6 63000 12983 1.421 ! Near Maximum !
Lovex D100 97.3 112.6 7.30 2729 98.0 63000 13106 1.411 ! Near Maximum !
Hodgdon H4831 91.3 95.4 6.18 2717 100.0 63000 11998 1.401 ! Near Maximum !

 

[Woodycreek]

That is one cool beast of a rifle! 2900 fps with a 300 gr AB is a screamer for sure.

 

[OU812]

Nice!
That wil be a long range hammer for sure. The 300 gr AB would be a top performer for sure with a MV of 2850-2900 fps.
I'm sure OU812 will come along shortly and share his loads with you.

JD338

OU812 no longer has any data for the 338-378 but I remember RL-25, IMR-7828 and H-1000 being top performers with 250 grain bullets in that order of speed and accuracy in my old 338-378.


Bill

 

[JD338]

That is one cool beast of a rifle! 2900 fps with a 300 gr AB is a screamer for sure.

Run it in a ballistic calculator and you will really be impressed.

JD338

 

[HOGWILD338-378]

I have had this rifle for a while now and have not shot it enough to get enough once shot brass to start load development but the factory stuff is very accurate in my rifle! Getting 3180 form some 225 Gr barnes TSX's and by far the most accurate rifle i own next to my 257 which shoots identical groups! I installed a Timney on my rifle and have it set to around 2 lb 10 oz! and hard to explain the smile i get when i shoot this thing but i do have some 300 Gr AB's and some SMK's to load for it once i set down and start load testing it! Still have a couple boxes of factory ammo and i always like to get around 100 rounds of once shot brass on a new caliber before i will load them! I am working on getting some 270 Wby brass as my Lazermark is a dream to shoot! Just ordered a Timney for my 270 Lazer last night!

 

[JD338]

Hog,

What are you using for glass?

JD338

 

[SJB358]

Very nice set up Terry! Those are some really sharp rifles!

 

[sask boy]

That is another one of those cannons that go fast and hit extremely hard at real long distances :wink:. They are a fine rifle.
Looking forward to your range report with photos I hope :wink:

Blessings,
Dan

 

[HOGWILD338-378]

Leupold Mark 4 #64660 Warne mounts! 6.5-20x50
It is a tack driver and next trip out i will do some pics!

 

[HOGWILD338-378]

I had Charley at Hi-Score gun shop here in ABQ install my optic as he had a jig setup that was supposed to be very accurate on alignment and he ran a work sheet once he aligned it but i still can't understand the worksheet that well?

He also did not know this was a LR/T Leupold but it is a FF optic and has not buckled with the recoil and if it does it can go back to Leupold!

 

[HOGWILD338-378]

When i do start loading i will just go with published minimums and work about 4 different loads at the same time watching for pressure signs as i shoot up thru the bigger loads? I have around 6 manuals with great data and once fired brass on hand now is around 60 rounds of factory stuff!

 

[boomer68]

I want to try the 300gr AB. Looks like a wicked bullet for long range. I also have some 250gr SMK for target use. Just got 7lbs of 7828ssc, so that might last a few reloads

 

[JD338]

I want to try the 300gr AB. Looks like a wicked bullet for long range. I also have some 250gr SMK for target use. Just got 7lbs of 7828ssc, so that might last a few reloads

About 549 rounds to be exact. :mrgreen:

JD338

 

[HOGWILD338-378]

I think that AB round would be a great Big Game round and your choice of powder looks really good! I need to pick some up myself, not sure I need that big a jug as I will try working up loads with 1 Lb cans! what kinda optik did ya put on your rifle boomer68? I will try some Retumbo myself also!

 

[JD338]

I think that AB round would be a great Big Game round and your choice of powder looks really good! I need to pick some up myself, not sure I need that big a jug as I will try working up loads with 1 Lb cans! what kinda optik did ya put on your rifle boomer68? I will try some Retumbo myself also!

I think Retumbo and the new RL 33, when it is finally released, will be a couple of good powders to try in that big 338-379 case.

JD338