338 Weatherby Magnum Vs 338 Lapua

Calibres, cartridges, ballistics tables and ammunition information.

338 Weatherby Magnum Vs 338 Lapua

Post by Die Judicii » 23 Mar 2017, 10:24 pm

A friend has asked, What is the difference btween 338 Weatherby Magnum and 338 Lapua.

Can you xperts out there shed some light on this ?

Trajectory/Range, velocity, ft/lb impact at ?????
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Re: 338 Weatherby Magnum Vs 338 Lapua

Post by bladeracer » 24 Mar 2017, 1:26 pm

Die Judicii wrote:A friend has asked, What is the difference btween 338 Weatherby Magnum and 338 Lapua.

Can you xperts out there shed some light on this ?

Trajectory/Range, velocity, ft/lb impact at ?????


I have zero experience on these, but I think the .338 Lapua has its reputation mainly due to it usually being barreled in a 9" twist. Otherwise the only differences are going to be from how much velocity you can make from the bullet and how much powder it takes to do so. I would consider the Weatherby to be a wildcat with the associated cost/supply restrictions both on the ammo and the rifles. You could probably make up the 3-5% more velocity by putting two inches on the Lapua's barrel length if you really needed it. Using the same bullets, 100fps is not going to have significant effect on trajectory or energy.

Looking at ADI data (Lapua from 24", both Weatherby's from 26" tubes):
The .338-.378 Weatherby makes about 100-150fps more velocity than the Lapua, but with 10-15% more powder.
The .340 Weatherby Magnum makes about 100fps less velocity than the Lapua, but with 15-20% less powder.

.338 Weatherby fires a 160gn at 3600fps, the Lapua at 3500fps. They push 300gn bullets at 2800fps and 2650fps.

Using the Hornady 250gn Interlock as an example:
At 2850fps the Lapua holds 800ft/lbs of energy out to 1000yds and goes subsonic very soon after that.
At 3050fps the .338-.378 WB adds about 90yds to those ranges.
At 2750fps the .340 Weatherby drops about 40yds off the Lapua's ranges.

From a 250yd zero:
.338 Lapua is 3.4" high at 150yds and drops 39" by 500yds.
.338-.378 Weatherby is 2.8" high at 150yds and drops 33.5" by 500yds.
.340 Weatherby is 3.7" high at 150yds and drops 42" by 500yds.

Just had a look at Brownells for price comparison of Norma brass:
.338 Lapua Magnum 100 cases are US$210.
.338-.378 Weatherby Magnum 100 cases are US$376.
.340 Weatherby Magnum 100 cases are US$204.
.338 WinMag 100 cases are US$138.
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Re: 338 Weatherby Magnum Vs 338 Lapua

Post by Die Judicii » 25 Mar 2017, 8:26 pm

Thanks heaps Blade,, I passed the info on
:thumbsup:
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Re: 338 Weatherby Magnum Vs 338 Lapua

Post by Bourt » 06 Apr 2017, 1:15 pm

$376US for 100 cases. Bugger me no thanks.
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Re: 338 Weatherby Magnum Vs 338 Lapua

Post by SCJ429 » 18 May 2018, 7:23 pm

Please forgive the thread mining but the world needs more 338 shooters.
The 340 is an awesome case but it has a belt, the 338 Lap is awesome also and is an excellent high intensity cartridge, also slightly quicker than the 340. The 338/378 is a romper stomper but it has a belt, I get looked down on by Lapua shooters when I show up with my Weatherby actioned 338/378 but I have not seen any accuracy advantage the Lapua shooters hold. Mine will shoot 300 SMK into .4 inch groups at 100 and 3 inches at 500. Don't expect to show up to a long range comp with romper stomper and show them how it is done. You will get beaten by every 6mm BR there and probably by some bloke with his trusty 223.
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