This old wildcat was finally legitimized by the relatively small A-Square loading company in 1998 and Weatherby is now producing factory made rifles for the cartridge. The industry standard pressure for the .338-06 A-Square has been set at 53,000 cup. The .338-06 is nothing more than the .30-06 case necked-up to accept .338" bullets, the same diameter used by the popular .338 Winchester Magnum.

Strange as it may seem, the .33-06 got a shot in the arm when the .338 Winchester Magnum was introduced. Although the .338 Magnum was ballistically superior to the old wildcat, its introduction and subsequent popularity made a variety of good .338" bullets widely available to reloaders in North America. The earlier .33-06, .333 OKH, etc. quickly evolved into the .338-06. All of these .33-06 Wildcats offer identical ballistics with modern powders.

The .338-06 has a couple of important advantages over the .35 Whelen, also based on a necked-up .30-06 case. The most important of these is that the amount of shoulder left after necking a .30-06 case up to .338 is greater than that left after necking the same case up to .358. The .35 Whelen has always been marginal at maintaining proper headspace against the blow of the firing pin due to its minimal 17.5 degree shoulder. (The original 17.5 degree shoulder angle of the .30-06 is unchanged in both the .338-06 and .35 Whelen cases.) The slightly larger shoulder area of the .338-06 case solves that problem.

Another advantage for the contemporary reloader is that there is a better selection of .338" bullets suitable for large game, in more weights, than there is of .358" bullets. The popularity of the .338 Magnum has insured that. Also, in any given weight, a .338" bullet has superior sectional density (SD) for deeper penetration than a .358" bullet. Given the same form and velocity a .338" bullet also has superior ballistic coefficient (BC) for a flatter trajectory compared to a .358" bullet of the same weight.

A-Square offers three factory loads for the .338-06. One drives a 200 grain Nosler Ballistic Tip bullet (SD .254, BC .414) at a muzzle velocity (MV) of 2750 fps with 3358 ft. lbs. of muzzle energy (ME). At 100 yards this bullet is traveling at 2553 fps with 2894 ft. lbs. of energy. At 200 yards the figures are 2364 fps and 2482 ft. lbs. At 300 yards the Nosler bullet is still traveling at 2184 fps and carrying 2118 ft. lbs. of energy.

This would seem to be an excellent general purpose load. Its trajectory is such that a bullet from a scoped rifle zeroed at 200 yards will strike 2.4" high at 100 yards and 8.2" low at 300 yards, making the .338-06 about a 275 yard big game cartridge.

The other two factory loads use 250 grain bullets (SD .313). These start with a MV of 2500 fps and a ME of 3496 ft. lbs. The more streamlined of the two, a boat-tail spitzer, is still traveling at 2134 fps and carrying 2528 ft. lbs. of energy at 300 yards. The drop at 300 yards is 9.3" from a rifle zeroed at 200 yards. The 250 grain bullets are probably best reserved for the largest game, such as moose.

For the reloader, bullets of 200, 210, and 225 grains are probably the most useful. Staying within permissible pressures, reloaders can equal, but not substantially exceed, the velocities of the factory loads. According to the fifth edition of the Nosler Reloading Guide their 210 grain Partition bullet can be driven to a MV of 2490 fps by 48.0 grains of IMR 4320 powder, and 2690 fps by 52.0 grains of IMR 4350. This should be an good all-around bullet in the .338-06, suitable for most thinned-skinned big game.

.338-06 bullet velocities trail those of the .338 Magnum by 150-200 fps, depending on bullet weight. Energy is proportionally less at all ranges, but remains sufficient for all North American big game, including dangerous game, at the ranges these animals are usually shot.

The recoil of the .338-06 is less than that of the .338 Magnum, but still substantial. According to the figures in the "Rifle Recoil Table," an 8 pound .338-06 rifle shooting a 200 grain bullet at 2800 fps belts the shooter with 23.9 ft. lbs. of recoil energy. The .338 Win. Mag. (200 grains at 2950 fps) records 32.8 ft. lbs. of recoil in an 8.5 pound rifle. The .338-06 offers serious punch and less recoil than the popular .338 Win Mag.