Compared: .30-06 Springfield and 8mm Mauser (8x57JS)
By Chuck Hawks
To many North American shooters and hunters, who are intimately familiar with the .30-06 but barely aware of the 8x57, this may seem like an odd comparison. Our European readers, however, will certainly understand that the 8x57JS is very comparable to the .30-06, both historically and ballistically.
These two cartridges were used on opposite sides in two world wars, and the industrial might of the Allied powers ultimately prevailed in both instances. Those victories were not, however, due to any great superiority of the American .30-06 Springfield service rifle cartridge over Germany's 8x57JS Mauser service rifle cartridge.
By way of brief background history, the US Army adopted the .30-06 Springfield cartridge in 1906. It was a direct response to the German Army's 1905 decision to load a .323" 150 grain spitzer (pointed) bullet at a very high muzzle velocity (MV) of about 2800 fps. This new projectile was loaded in the case of their existing 8x57 (7.92mm or .318" bullet) service rifle cartridge, thus creating the 8x57JS with which Germany fought the First (and later the Second) World War.
The U.S. had adopted the .30-03 (using a 220 grain RN bullet at around 2400 fps), the predecessor of the .30-06, in 1903. The advent of the 8x57JS immediately made the new .30-03 American service cartridge, with its round nose bullet and rainbow trajectory, obsolete.
The U.S. Army quickly responded by loading a lighter spitzer bullet at higher velocity in their service cartridge. The new load used a 150 grain bullet at a MV of 2700 fps and was adopted in 1906 as the .30-06. So, you see, it was actually the 8x57JS that was responsible for the creation of the .30-06.
The .30-06 and the 8x57JS were both quickly adapted to hunting rifles and loaded with various bullet weights, and went on to become popular worldwide. Ammunition for both is offered on every continent where big game is hunted. The .30-06 ultimately became the most popular big game hunting cartridge in the world, but the 8x57JS is still very popular in most of Europe and 8x57JS ammunition is widely distributed in Africa. In the U.S. the cartridge is usually called the "8mm Mauser."
8mm Mauser ammunition is widely but thinly distributed in North America. U.S. factory loads are few and mostly loaded to much lower pressure (37,000 cup) than European 8x57JS ammunition (about 50,000 cup). Essentially, modern US 8mm Mauser ammo is loaded to the old 8x57 pressure level, but with .323" diameter bullets. This is allegedly due to our inability to distinguish between the original 8x57 (.318" bullet) and later 8x57JS (.323" bullet) rounds, which use the same case but different bullets loaded to different pressure and velocity.
For the purposes of this article we are going to compare full power loads in both calibers that are equivalent to European 8x57JS and American .30-06 factory loads. And, because European and American factory loads for the two calibers use bullets of different designs and slightly different weights, to keep the comparison as fair as possible we will standardize on 150 grain and 200 grain Speer Hot-Cor, flat base bullets. These bullets, which Speer describes as "spitzer soft point" bullets, are offered to reloaders in both calibers. Our comparison loads will use 150 grain bullets at a MV of 2900 fps, and 200 grain bullets at a MV of 2500 fps in both calibers.
We will compare these loads in bullet ballistic coefficient (BC), sectional density (SD), and cross-sectional area. We will then go on to look at velocity, kinetic energy, trajectory, killing power, and recoil. And we will conclude with a few comments about rifle and cartridge availability.
The Speer Reloading Manual No. 13 defines sectional density as, "A bullet's weight in pounds divided by the square of its diameter in inches." SD is important because it affects bullet penetration. When comparing two bullets of equal weight and construction but different diameters, the more slender bullet will tend to penetrate deeper if other factors are equal. In big game hunting, this translates to a longer wound cavity. Here are the SD numbers for our chosen bullets.
The .30-06, due to its smaller bullet diameter (.308" vs. .323") has the advantage in SD. As a practical matter, sectional densities in the range of .205-.226 are regarded as excellent for deer and other CXP2 game, while a sectional density of around .255 and above is favored for CXP3 game like elk and moose. Both the .30-06 and 8x57JS are fine all-around cartridges for use, with proper bullets, on a wide range of CXP2 and CXP3 game.
The Speer Reloading Manual No. 13 defines ballistic coefficient as, "Ratio of sectional density of a bullet to its coefficient of form. Represents the projectile's ability to overcome the resistance of the air in flight." In other words, the higher the BC number the lower the air drag. BC is important because a more streamline bullet will shoot flatter over extended ranges and also retain more of its initial energy. Here are the Speer BC numbers for our sample bullets.
The .30-06 has the advantage in BC given bullets of the same approximate form due to its superior SD. We will soon see what advantage this confers downrange in terms of energy and trajectory.
Cross-sectional area (frontal area) is important because, when comparing two bullets of equal construction and expansion ratios but different diameters, the fatter bullet will make a wider wound channel, thus destroying more tissue in the game animal. Note that bullet weight has no affect on cross-sectional area. The actual diameter of .30-06 bullets is .308", and the actual diameter of 8x57JS bullets is .323". Here are the cross-sectional areas (in square inches) of our two calibers.
Naturally, the fatter 8x57JS bullet has the advantage in cross-sectional area. In terms of terminal ballistics in big game animals, if the differences are not excessive, cross-sectional area and sectional density tend to cancel each other out in regards to the total amount of tissue disrupted. The one results in a wider wound channel and the other results in a deeper wound channel.
For the purposes of this comparison, we are starting out our .30-06 and 8x57JS bullets at the same muzzle velocity. However, due to the difference in BC, the downrange velocities will differ. Here are the Speer velocity figures for our four loads (in feet per second) from the muzzle to 300 yards.
As can be seen from these velocities, there is really very little difference between the two 150 grain bullets. They have similar BC's and that results in similar downrange velocities. But the very high .556 BC of the 200 grain .30-06 bullet gives it a substantial velocity advantage over the 200 grain 8mm bullet at long range.
Kinetic energy is loosely defined as the ability to do work. The "work" in this case is powering bullet expansion and penetration to create the largest possible wound cavity. Energy is an important factor in killing power and it is commonly used to compare the power of various rifle cartridges. Practically all factory ballistics tables show both velocity and energy figures. Here are the energy figures (in foot pounds) for our selected loads at the muzzle (ME), 100, 200, and 300 yards.
These figures demonstrate that, once again, there is little to choose between the two cartridges when shooting the Speer 150 grain bullets. The slightly superior BC of the .30-06 bullet results in an advantage of only 50 ft. lbs. of energy at 300 yards, which is inconsequential on CXP2 game.
The 8x57JS falls a little farther behind when the Speer 200 grain bullets are compared. Here the difference in energy at 300 yards amounts to 254 ft. lbs. This is due to the very high .556 BC of the Speer .308" bullet. Still not a vast disparity, and I doubt that your average CXP3 game animal could live on the difference, but it does represent a slight advantage for the .30-06.
Trajectory matters because the flatter a bullet shoots the easier it is to place it accurately downrange. And bullet placement is by far, the most important factor in achieving quick, clean kills with any caliber of hunting rifle. Here are the trajectory figures for our selected loads in inches above or below the line of sight at 100, 200, and 300 yards.
There is no practical difference in the trajectories of the 150 grain bullets from the muzzle to 300 yards, and precious little difference between the 200 grain bullets. The .30-06 has a slight advantage on paper with 200 grain bullets, but considering the 10" vital area of even modest size CXP2 animals, a maximum difference in bullet drop of only 0.8" at 300 yards is of very little importance in the field.
OGW Killing Power
The hardest factor to quantify is killing power, and all attempts to do so must be approximations. We know that energy, penetration, and bullet frontal area (among others) are all important factors in killing power, but not exactly what is the best blend of these factors.
Edward A. Matunas devised, and the Lyman Reloading Manual, 47th Edition published, the formula used to determine the optimal game weight (OGW) for which rifle cartridges are suitable at various ranges, assuming bullets of adequate penetration and expansion for their intended application. OGW is a system intended to express the killing power of rifle cartridges in terms of an animal's live weight and the optimum distance at which it should be taken with a given cartridge and load. Thus it compares the killing power of different cartridges and loads in a way that is relevant in the field.
The OGW formula is not perfect, but when used to compare similar rifle cartridges, as we are doing, it seems to have a positive correlation with reality. Here are the OGW figures (in pounds) for our selected loads at the muzzle, 100, 200, and 300 yards.
Once again there is little to choose between the 150 grain bullets in these two calibers. Either is suitable for the largest CXP2 game at 300 yards and beyond. The 200 grain bullets are a different story, with the .30-06 showing just over a 100 pound (about 20%) advantage in OGW at 300 yards, although the two calibers are equal at the muzzle.
This category becomes increasingly important as recoil energy approaches the 15-20 ft. lb. level. Somewhere in there is the typical hunter's sustained recoil tolerance limit. Heavy recoil encourages flinching, which is poisonous to accurate bullet placement. And, bullet placement is, need I repeat, the most important factor in killing power. Always consider recoil when planning the purchase of a new hunting rifle.
Here are some approximate recoil energy (in foot pounds) and velocity (in fps) figures for our selected loads when fired in 8.0 pound rifles. For computational purposes, RL-15 powder was chosen for the 150 grain bullets in both calibers, while RL-22 powder was chosen for the .30-06/200 and H380 for the 8x57/200.
Heavy bullets generally kick harder than lighter bullets, as illustrated here. Because the performance of these two calibers is so similar, so is the recoil. Interestingly, the 8x57JS actually requires more RL-15 powder to drive its 150 grain bullet to 2900 fps than does the .30-06, despite the latter's slightly greater case capacity. That is an anomaly that I can't explain. Presumably the difference had something to do with the specific rifles tested. But, in any case, 0.6 ft. lb. is not a lot of difference in recoil energy, and most shooters will probably be able to handle either caliber shooting 150 grain bullets.
A bit more significant is the recoil energy with 200 grain bullets. Here we are right at, or slightly beyond, the theoretical maximum for most shooters. And the .30-06 delivers 1.3 ft. lbs. more recoil than the 8x57JS with our selected loads. Which probably helps to explain why few .30-06 owners ever shoot bullets heavier than 180 grains, a load that typically delivers right at 20 ft. lbs. of recoil energy in an 8 pound rifle. The SD of that bullet is .271, by the way, which makes it very comparable to the 200 grain 8mm bullet.
As the foregoing shows, there is precious little practical difference between the .30-06 and the 8x57JS. While the .30-06 has an advantage in SD with any given bullet weight, the 8x57JS has a compensating advantage in cross-sectional area. In most other areas the .30-06 has a slight advantage on paper, but little or no significant advantage in the field. You could generalize by saying that the two are essentially equal as hunting cartridges and get no argument from me.
This may come as something of a shock to many North American hunters, who are accustomed to the ballistics of low pressure SAAMI 8mm Mauser factory loads, but it will not surprise European hunters who regularly buy and shoot full power 8x57JS ammunition.
The real difference between the two cartridges for someone looking to buy a hunting rifle in one of these two calibers is the availability of rifles and factory loaded ammunition. Certainly in North America, and probably in most of the world, the .30-06 is more common in both rifles and variety of factory loaded ammunition than the 8x57JS. The 8x57JS is popular and readily available in most of Europe and much of Africa, but so is the .30-06. There are no flies on the 8x57, but when push comes to shove it is pretty hard to beat the .30-06 as an all-around, worldwide caliber for CXP2 and CXP3 game.
Copyright 2007, 2012 by Chuck Hawks. All rights reserved.