L-R - .338 Win. Mag., .338 Ultra Mag., .340 wetherby Mag.

.338 Cartridge Comparison

L-R - .338 Win. Mag., .338 Ultra Mag., .340 wetherby Mag.
L-R – .338 Win. Mag., .338 Ultra Mag., .340 Weatherby Mag.

Q; The barrel on my Remington 700 in 8mm Rem.Mag. is burned out and I have over two hundred new 8mm Rem. Mag. cases on hand as well as over 100 once fired cases. I was thinking of getting my rifle rebarreled for a wildcat – .338-8mm Rem. Mag. no less. How would the .338-8mm Rem. Mag compare with the .338 Lapua Mag., or the .340 Weatherby Mag. and ,338 Ultra Mag. at long range when loaded with 250gn bullets?
Cecil Roberts

A: Case capacity of the .338-8mm Rem. Magnum is almost identical to that of the .340 Weatherby, so when they are both loaded with 250gn bullets, their maximum velocities are the same at about 2900fps. It so happens that the case capacities of the .338 Lapua Magnum and the .338 Remington Ultra Mag (and the .338-378 Weatherby) are nearly the same, so their maximum velocities are about the same – 3000 fps with 250gn bullets. If I were you, I’d forget about a .338 wildcat on the 8mm Rem. Mag. case and choose the .340 Weatherby Magnum over the .338 Lapua or .338 Ultra Mag due to the availability of factory ammo and uprimed brass because those two generate more recoil and are only 100fps faster. With the same case rim diameter it will work in your action without any modifications and dies are easy to get.




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Nick Harvey

The late Nick Harvey (1931-2024) was one of the world's most experienced and knowledgeable gun writers, a true legend of the business. He wrote about firearms and hunting for about 70 years, published many books and uncounted articles, and travelled the world to hunt and shoot. His reloading manuals are highly sought after, and his knowledge of the subject was unmatched. He was Sporting Shooter's Technical Editor for almost 50 years. His work lives on here as part of his legacy to us all.