The venerable .30-06 Springfield cartridge has been the parent of numerous wildcat cartridges, some of which have gone on to become established cartridges in their own right. Among them is the .338-06, standardized by SAAMI as the .338-06 A-Square.
The .338-06 has its origins in the popularity of .33-caliber medium bore cartridges before the 1950s. Numerous cartridges featuring .330” and .333”-diameter bullets were popular at the time, including the .318 Westley Richards, the .333 Jeffery, and the .333 OKH.
The .333 OKH is the immediate predecessor of the .338-06, being a .30-06 case necked up to take .333”-diameter bullets. With the waning popularity of the Jeffery and Westley Richards cartridges, supplies of .330” and .333”-diameter bullets largely dried up.
And as the .338 Winchester Magnum gained popularity, .338”-diameter bullets became more widely available. It was only logical, then, that wildcatters would begin to used the .338-caliber bullets in the .30-06 case, and thus the .338-06 was born.
The .338-06 largely duplicated the performance of the .333 Jeffery and the .318 Westley Richards, but without requiring proprietary and difficult to acquire brass. With .30-06 being plentiful, a simple necking up operation was all that was necessary to form brass to .338-06. Add a new barrel to an existing .30-06 action, and you had a rifle that was capable of taking most game in North America and many African plains game species as well.
The .338-06 is capable of pushing a 200-grain bullet to 2,860 feet per second, a 225-grain bullet to 2,730 feet per second, and a 250-grain bullet to 2,570 feet per second, giving around 3,700 foot-pounds of muzzle energy. That’s a significant jump over the power of the .30-06.
The .338-caliber bullets also have very high sectional density, allowing them to penetrate deeper, and have better long range ballistic performance than other medium-bore calibers such as .358 and .375. That makes them popular for shooting large game out to several hundred yards.
For instance, a 250-grain .338” bullet leaving the muzzle at 2,570 feet per second will have 8% more energy than a 200-grain .30-06 bullet at 300 yards, with only 1.5” more drop. And that .338-06 cartridge can do that while still fitting into a standard long action.
Compared to larger cartridges like the .338 Winchester Magnum, the .338-06 uses less powder, suffers less recoil, and can often produce muzzle velocities within about 100 feet per second of the .338 Win. Mag. And with brass being cheap and plentiful, it’s much easier for handloaders to make ammo.
Where .338-06 doesn’t shine is when it comes to factory ammunition. Right now there’s basically nothing available, and you’ll have to pay several dollars a round if you’re able to find anything. That makes .338-06 more or less a handloading-only proposition.
So the long and short of it is that the .338-06 is a perfectly viable survival cartridge. But unless you’re willing to learn how to handload and build up a sufficient supply of ammunition, you may be better served by other cartridges.
