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Bullet diameter is a true .338 inch unlike some of the early .333 caliber cartridges. Winchester launched the cartridge with a choice of two bullet weights – a 200gn Power Point with a nominal muzzle velocity of 3000fps and a 250gn Silvertip at 2700fps. Then in 1961, a third loading with a 300gn round-nose Power-Point bullet at a listed 2450fps was added. Maximum chamber pressure was listed as being 53,000 psi. For whatever reason, muzzle velocities were later reduced to 2960, 2660 and 2430fps respectively albeit from a 600mm barrel.
Today Winchester offers four different loads for the .338 – three with 200gn bullets – a 200gn Power Max Bonded, a 200gn Ballistic Silvertip and a 200gn Power Point – all with a muzzle velocity of 2960fps; and a 225gn ABCT at 2800fps. Other ammo makers load much the same bullet weights, but different designs. Federal loads an ‘180gn’ AccuBond at 3120fps; a 210gn Partition at 2830; a 225gn Barnes Triple Shock at 2800; a 225gn Trophy Bonded Bear Claw at 2730; and a 250gn Partition at 2660fps. These velocities were obtained from a 600mm barrel and can be equaled by hand loaders without exceeding safe pressure limits.
Why Winchester chose a .338-inch caliber over .358 has puzzled many gun writers, many of whom have come up with some fanciful theories. But Winchester was probably influenced to a great extent by Elmer Keith’s writing about the effectiveness of his .333 OKH Belted wildcat. As to why they chose .338 instead of .358 is easy to answer. For one thing .338 bullets have better sectional densities than those of the same weight in .358" diameter. To equal the 250gn .338 bullets S.D of .313, a .358 bullet would have to weigh 281 grains.
Many hunters feel the 200gn bullet is the best medicine for game at long range because of the 3000fps the .338 drives it at. However, this is largely dreaming for the 200gn bullet has far less sectional density and ballistic coefficient than the 180gn .30 caliber bullet, which does not result in either a flatter trajectory or deeper penetration. Second, apart from the Nosler AccuBond, I have never found a 200gn bullet that would hold together and not expand too rapidly on heavy game. Most work very well on thin-skinned medium-size game like deer, but lack enough penetration for large, heavy-boned game.
For the deer hunter, the 210gn Partition is another good choice, but Barnes X-Bullets are in a class of their own. The 185gn MRX BT has greater S.D and B.C than most 200gn bullets and is more strongly constructed. However, the 210 gn TSX bullet which starts out only 100fps slower than the 185 grainer has better S.D and B.C – .263 and .404 – against .231 and .379 for the 185gn MRX. But the 210gn’s major advantage is that it does not blow up at any range even from striking heavy bones at short range. I have driven the 210gn TSX BT at 2900fps with a stiff charge of Re-19 from a 600mm barrel, and my tests have shown that it drops less at 400 meters than the 185gn that started out at 3200fps. Sighted in 70mm high at 100 meters for a 225m zero, the 210gn TSX FB bullet drops 620mm out at 400, and packs 1822 ft/lb of energy.
The Barnes 185gn MRX which starts out 300 fps faster, follows substantially the same trajectory path out to 300m, but drops 50mm less than the 210 grainer at 400 and delivers 93 ft/lb more energy. Not enough difference to worry about.
The 225gn Hornady SST with its S.D of .281 and B.C of .515 is a very efficient choice for long range deer shooting in the .338. Boosted out at 2850fps, and sighted in for a 225m zero, the SST lands 75mm high at 100m, is still 36mm high at 200, drops 176mm low at 300 and 584mm at 400. Remaining energy at 400 is 2239 ft/lb.
The 225gn bullet is the weight I mostly use in my own long-throated .338 Whitworth Express, which gets both Hornady and Barnes-X out at over 2900fps with a heavier charge of Re-19 than would be safe in a standard .338 throat. Water capacity in a normal .338 rifle with standard length action and chamber, is an indicator of how much powder you can use behind bullets of different weights and lengths. In a standard-length throat it reduces from 78.6gn with a 180gn bullet to 76.8gn with 200-210gn, to 76.4gn with a 225gn, 73gn with a 250gn, and 70gn with a 300gn longster. My .338 Whitworth Express, built on a full-length Mark X magnum action has a long throat which allows bullets to be seated so that their bases don’t extend below the case necks. This increases the usable powder space boosting the .338’s performance, and has it treading close to the .340 Weatherby. The Hornady 225gn SST holds together well at 300 meters or more, but at closer ranges it is likely to break apart on big animals if heavy bone is encountered.
My old pal Elmer Keith never considered anything lighter than 250gn in his .33 caliber rifles for game at any distance, but much-preferred heavy 275 and 300gn bullets. While 250gn may be the optimum weight for shooting big, heavy game at ranges up to 250 meters or so, I prefer a stoutly structured 225gn bullet with a spritzer shape for all around use. Current lighter weight bullets give better terminal performance, penetration, accuracy, and flatter trajectories. Nosler’s 250gn AccuBond with its high B.C of .575 is one of the best .338 bullets made as far as long range shape is concerned. This extreme B.C coupled with the high S.D of .313 gives it a retained energy of 2353 ft/lb at 400 meters. It can be driven at up to 2780fps with a max’ charge of AR22113sc, but this may be too hot in some rifles, so I’d recommend using 2 grains less powder. A loss of only 70 foot-seconds is not going to make enough difference in drop to be noticeable in the field. Sighted 76mm high at 100m it is 44mm high at 200, drops 195mm at 300 and 635mm at 400.
This controlled expansion bullet has good B.C, expanding well at any reasonable velocity to have a large frontal area that destroys plenty of tissue on broadside lung shots. Yet its high weight retention will give extremely deep penetration for the heaviest game.
The kinetic striking energy of the 250gn AccuBond from the .338 Magnum is about 25 percent greater than the .30-06 and about the same as the .300 Win. Mag. with 180gn bullet, but having 20 percent greater cross-sectional area and 70 grains greater bullet weight contributes materially to the superiority of the .338.
Most of my experience with the .338 Win. Mag.was gained with my first rifle, a Ruger Number One with 650mm barrel, which I used very successfully on deer and buffalo. Reloading the strong case is straightforward. Differences in brass thickness and case capacity vary from one maker to the next, and even in different lots from the same maker. Measuring water capacity of more than half a dozen cases from major U.S makers, weight ranged from 73.8 to 78.6 grains. This makes it necessary to vary loads a little when changing brass, but doesn’t affect me, as I use only Winchester brass. New primed cases weighed 239.8 grains and held 76 grains of water filled to the base of the neck.
With any belted magnum case, however, care should be taken when full length sizing that the die doesn’t set case shoulders back; size cases only enough to allow them to headspace on the shoulder just like a rimless case. After sizing with the die turned down in the press so that it clears the shell holder by about 7mm, try the resized case in the rifle it will be used in. If it is the least bit tight, turn down the die just a little and try again. By repeating this operation until the case chambers freely, you will have a reload that will give no chambering problems in the field. This method should also help to extend case life.
Using this technique with the .338 I have never struck any problems with short case life although as with any high intensity cartridge, primer pockets tend to expand slightly after a number of warmish loads, but as a rule not enough to ruin cases. In fact, I’ve yet to experience a single instance of case failure and have never had to junk a single case.
Case resizing is important to the hunter because in the field, ammunition should always chamber easily in the rifle it is used in. For this reason neck sizing only is not recommended for hunting reloads. No amount of resizing, however, will cure a neck that’s too long for the chamber. Be sure to keep reloaded cases trimmed down to the length of a new, unfired factory case. And of course, always run every reloaded round through the magazine and chamber of your rifle before you take it hunting.
Powder selection for the .338 is not so cut and dried as one might imagine. I’ve found that powders with medium slow burning rates such as AR2209, Re-19, and W-760 work well with bullets weighing from 180gn to 250gn giving the highest velocities and best accuracy. Velocities fall off dramatically when real slow burners are used, but with the heaviest bullets available in .338 – the 300gn AccuBond and Woodleigh’s 300gn RNSN or FMJ – AR2213sc and Supreme 780 work just fine.
Developing effective working loads while staying within pressure limitations, the highest velocities with 180, 200 and 210gn bullets are achieved using W-760 and Re-19 respectively. Although Re-19 trumped AR2209 with 225gn bullets, the order was reversed with the 250 grainers.
If I were obliged to choose just one powder for the .338 it would be AR2209 or Re-19. Both give high velocity and the good accuracy. In the Winchester brass I am using, it was impossible to get in large enough charges of bulky slow-burning powders to equal the velocities gained with AR2209 and Re-19. All my charges measured on a Hornady Lock N’ Load Auto Charge Powder Dispenser and dribbled into the cases through a funnel with a long drop tube gave near 100 percent load density without any heavy compression. These two powders offer an optimum combination of bulk and burning rate while burning cleanly with magnum primers.
If a hunter feels that he is better off starting a 180gn bullet like the AccuBond at around 2700fps for a specific hunting condition, then in my opinion, it would be better loaded in a .338-06 case instead of the .338 Magnum. Reducing loads and velocities in large capacity cases is not always successful with regard to accuracy. It is generally assumed that if the powder charge is dropped a few grains below maximum, accuracy will be greatly improved. This may be true with small to medium capacity cases, but not magnum cases, and it doesn’t always prove true with all of the smaller cases either. I’ve found after many years of reloading magnum cartridges, that with most bullets, and particularly the heavier weights, the best accuracy comes with loads as hot as the case will stand without causing pressure problems. The .338 Magnum is no exception to the rule.
In recent years the .338 Win. Mag. has received a lot of competition from other .338 calibre cartridges. The .338-06 probably has more thump than the .30-06 and may be a capable deer rifle, but the improved .338-06 (8.5x63mm) does little more, than the .338 RCM (Ruger Compact Magnum). But none are anywhere near the equal of the .338 Win. Mag. on large and dangerous game.
The .340 Weatherby Magnum shades the standard .338, but my .338 Whitworth Express is close to it. The .340 Weatherby started out in life as an experimental cartridge made by necking down the 378 Weatherby to .338 with no other change. But finding that huge case was far overbore capacity for existing powders at that time, Weatherby used the .300 case to form his .340 Weatherby by simply expanding the neck.
When ultra-slow powders became available, Weatherby resurrected the .338-378, but although this impressive performer delivers extra retained energy and a flatter trajectory than any 7mm or .30 magnum with bullets of similar S.Ds it more or less duplicates the ballistics of the .338 Lapua and .338 Remington Ultra Mag. This trio of powerful cartridges doesn’t seem to have aroused much interest, probably because they kick like a team of mules!
In the 58 years since its introduction, the .338 Winchester Magnum has become a standard for North American big game. It’s a good choice for synthetic-stocked and laminated, stainless steel bolt-action rifles like the Ruger M77 Hawkeye, Remington Model 700, Browning’s X-Bolt and A-Bolt and the Winchester Model 70 Extreme Weather. Bullet selection in .338 covers everything from deer to dangerous game making it a versatile choice for the one-gun man, if such an individual really exists.