So, that standard short action just isn’t cutting it for down range power anymore? Perhaps you settled on a magnum but just can’t decide between the 300 Win Mag and the 338 Lapua Magnum. Both cartridges offer excellent long-range capabilities, so we will be discussing the benefits and drawbacks of each to help make your decision a little easier.
Other than sharing a large rifle primer pocket, the 300 Win Mag and the 338 Lapua could not be further apart in terms of design. The first difference you may have noticed is that the 338 Lapua is taller than the 300 Win Mag. An empty 300 Win Mag case stands at a nominal length of 2.62”. An empty 338 Lapua case, on the other hand, stands at a nominal length of 2.724” or just over a full hundred thousandths taller than the 300 Win Mag.
Height aside, the next difference you’ll probably notice is how much wider the 338 Lapua is compared to the 300 Win Mag. This extra width gives the 338 Lapua an H2O capacity of approximately* 116 grains. The 300 Win Mag, by comparison, has an H2O capacity of approximately* 94 grains, or 81 percent the capacity of the Lapua.
Along with the body of the 338 Lapua being wider than the 300 Win Mag, you’ll probably notice this same trend towards the base of each case. The 338 Lapua uses a rimless design which creates a very sleek profile. The 300 Win Mag uses a belted rim which is the protruding portion you can see at the base of the case.
The belted magnum rim is an old design but is very common amongst some of the many popular magnum cartridges. Like many of these other belted magnums, the 300 Win Mag uses a standard magnum bolt face with a rim diameter of 0.532”. The 338 Lapua uses a much less common rim diameter of 0.588”.
The last difference you may notice is the projectiles that each is using. As the name suggests, the 338 Lapua utilizes bullets that are 0.338” in diameter. Bullets in this diameter range from 160 grains up to 300 grains, with the 338 Lapua is primarily loaded with bullets in the heavier end of this spectrum. The 300 Win Mag on the other hand, uses 30 caliber bullets, or 0.308” in diameter. Bullets in this diameter range from 160 grains up to 300 grains, with the 338 Lapua primarily being loaded with bullets in the heavier end of this spectrum.
Although the 338 Lapua and the 300 Win Mag are both very powerful cartridges, they are very different when it comes to muzzle energy. Typical factory load offerings for the 300 Win Mag fall somewhere between 3,500 to 3,650 ft/lbs. of kinetic energy at the muzzle. However, loads like Federal Premium’s Gold Medal Berger 215 grain can produce more than this range at 3,877 ft/lbs. of kinetic energy at a muzzle velocity of 2,850 feet per second.
Nearly 4,000 ft/lbs. of muzzle energy is nothing to scoff at; however, the 338 Lapua is a different beast altogether. Factory loads for the 338 Lapua generally fall somewhere between 4,800 to 5,000 ft/lbs. of kinetic energy at the muzzle. However, loads like Black Hills’ 300 grain Sierra Matchking can exceed this range, producing 5,223 ft/lbs. of kinetic energy at a muzzle velocity of 2,800 feet per second.
With the max loads referenced for each cartridge, the 338 Lapua produces 1.35 times the power of the 300 Win Mag at the muzzle. This is an impressive figure, but we must remember that this energy must go somewhere. Assuming that both cartridges are fired out of the same weight firearm, the 338 Lapua is producing around 1.85 times the recoil of the 300 Win Mag.
Compared to the difference in muzzle energy between these cartridges, this is a substantial increase in recoil. This increase in recoil is a major drawback for long range shots, where it would likely take you further off target (without proper mitigation).
When it comes to long range potential, these cartridges have quite different capabilities in terms of factory loaded ammunition. Although the 300 Win Mag has excellent long-range potential, factory loadings typically consist of short, hunting style bullets that fit inside the magazine restrictions found in many 300 Win Mag chambered hunting rifles. Often, these bullet types do not have high ballistic coefficients; however, there are a few factory loaded options for the 300 Win Mag that offer good long range performance.
If we look at Federal Premium’s Gold Medal Berger in 300 Win Mag, we see that it launches a 215 grain Berger Hybrid at 2,850 feet per second. With a G1 ballistic coefficient of 0.691 and a muzzle energy of 3,877 ft/lbs., this load has a maximum supersonic range of around 1,700 yards (right under a mile), where it is carrying 615 ft/lbs. of kinetic energy.
Unlike the 300 Win Mag, which is primarily offered in hunting configurations, the 338 Lapua is a purpose-built, long-range cartridge. Although it is a very effective hunting cartridge, most factory load offerings for the 338 Lapua consist of heavy, aerodynamic projectiles to maximize long range potential.
If we look at Berger’s Match Grade Ammunition in 338 Lapua, we see that it launches a 300 grain Hybrid OTM at a muzzle velocity of 2,725 feet per second. With an astonishing G1 ballistic coefficient of 0.822 and a muzzle energy of 4,947 ft/lbs., this load has a maximum supersonic range of around 1,910 yards, where it is carrying 859 ft/lbs. of kinetic energy.
Based on these figures, the 338 Lapua has a distinct advantage when it comes to mass produced factory ammunition. However, many advancements have been made in terms of bullet technologies that favor the 30 caliber bore size. If a rifle has a fast enough twist rate, modern heavy-for-caliber 30 cal projectiles completely change the long-range potential of large 30 caliber cartridges.
Without getting into custom machined 30 caliber monolithic bullets, the Hornady 250 grain A-Tip (0.308”) has one of the highest G1 ballistic coefficients of any 30 caliber bullet, at 0.878. At a muzzle velocity of 2700 fps, this ballistic coefficient gives the 300 Win Mag a supersonic range of approximately 2110 yards. That is 200 yards further than the 338 Lapua load previously referenced, where it is still carrying about 715 ft/lbs. of energy.
Obviously, there have been advancements in the 338 bore size as well, but not quite as substantial as the 30 caliber bore size. Without getting into custom machined 338 caliber monolithic bullets, the Hornady 300 grain A-Tip has one of the highest G1 ballistic coefficients of any 338 diameter bullet, at 0.863. At a muzzle velocity of 2680fps, this extends the supersonic range of the 338 Lapua to around 2060 yards, where it is carrying around 858 ft/lbs. of kinetic energy.
Although the 300 Win Mag may not carry quite as much kinetic energy at these ranges, it surpassed the supersonic range of the 338 Lapua by 50 yards (with the loads referenced*). It should be noted, however, that most factory rifles chambered in 300 Win Mag utilize a 1-10 twist rate. This twist rate stabilizes most factory ammunition offerings with ease, however, when you start looking into heavy-for-caliber 30 cal projectiles (~230 gr and heavier), this twist rate is not sufficient.
This is an important consideration as many factory chambered 338 Lapua rifles utilize a twist rate fast enough to stabilize even the heaviest of projectiles available. It is also important to consider that many factory chambered 338 Lapua rifles offer a relatively long magazine length to accommodate for these longer projectiles. In general, factory chambered 300 Win Mag rifles offer relatively short magazines, meaning that long 300 Win Mag offerings may need to be single fed.
If you need a hard hitter at extended ranges, the 300 Win Mag and the 338 Lapua are both excellent choices with great capabilities. As with most cartridges, however, there are benefits and drawbacks to each.
Paired with a modern, heavy-for-caliber aerodynamic projectile, the 300 Win Mag can exceed the supersonic range of the 338 Lapua in some cases. Realize, however, that these figures are generally only achievable with custom/reloaded ammo as well as a custom rifle. Factory rifles chambered in the 300 Win Mag almost never have a fast enough twist rate to stabilize these projectiles.
Because the 338 Lapua was designed around long and heavy projectiles, many of the factory rifles chambered in the cartridge are well suited for most conventional 338 Lapua loads. At the muzzle, the 338 Lapua is a force to be reckoned with in terms of muzzle energy. Although this muzzle energy is impressive, it also generates a lot more recoil than the 300 Win Mag as well (assuming the same rifles), which is a major factor to consider.
Perhaps the biggest factor as to whether you choose a 300 Win Mag or a 338 Lapua, is cost. Regardless of whether you’re reloading or buying factory ammo, the 338 Lapua will almost always be more expensive than 300 Win Mag. Though this may be a drawback to some, both cartridges are excellent options for down-range power, and it would be hard to go wrong with either.
*H2O capacities may vary from the values referenced depending on the manufacturer of the case. The supersonic range values were gathered using a ballistic app with a reference value of sea level at 80 degrees Fahrenheit with 78% humidity. Hornady A-Tip velocities were taken from Copper Creek Cartridges Company.