Want Better Sectional Density? Here are Some Common Cartridges and Loads that Deliver
By Chuck Hawks
If you have been reading Guns and Shooting Online articles about the penetration advantage of bullets with high sectional density (SD) and would like a synopsis of the common cartridges and loads that deliver, this article is for you. For the purposes of this article, "high" means SD's over .280, which (if the bullet chosen were otherwise suitable) would mean a bullet well suited to harvesting the largest CXP3 game (elk, moose, oryx, etc.). Not all of the cartridges and loads mentioned are necessarily the best choice for hunting CXP3 game; there are other factors to consider in addition to SD. However, properly placed with bullets that expand appropriately, these loads will suffice and they will also do nicely for all species of CXP2 game (deer, sheep, pronghorn, goats, etc.).
Only commonly available, factory loaded, bullet weights are considered here. You don't have to handload or invest in special bullets to realize the advantage of superior SD with these cartridges. Nor are the loads mentioned below unusual in any way, they are standard fare.
Because of that requirement, some calibers/bullets have been excluded. The 220 grain bullet for the .30-06 is one such example. Although 220 grain bullets are available in factory loads, the heaviest bullet popular for use in any of the .30-.303 caliber cartridges weighs 180 grains and most .30-06 owners have never hunted with a heavier bullet, or even fired a 220 grain factory load. Thus, such loads are not included here.
No caliber below .26 is commonly loaded with bullets offering a SD of .280 or better, so the place to start is with the .264/6.5mm cartridges. The 6.5mm's give the most penetration for the least recoil of any family of cartridges. There are several popular European 6.5mm hunting cartridges, from the 6.5x54 M-S to the 6.5x68 Schuler, but few of these are known to most North American shooters and there are only a relatively small number of home grown .26's. The calibers most widely available to the North American shooter include the .260 Remington, 6.5x55 SE, 6.5-284 Norma, 6.5mm Remington Magnum and .264 Winchester Magnum.
These are all good cartridges, perfectly capable of handling the 140 grain spitzer bullets that sustain the caliber's reputation. A 140 grain, .264" diameter bullet has a SD of .287 and the standard 6.5mm cartridges can deliver this bullet with minimum fuss and recoil. A 6.5mm, 140 grain boat-tail spitzer bullet can also be designed for a very high ballistic coefficient, making it ideal for extreme range target shooting. That is why so many long range match winners are shooting 6.5mm cartridges.
Among all hunting calibers, the 6.5mm clan must be rated the top giant killers. They have been used repeatedly on all of the world's big game, up to and including African elephant. The 6.5x55 is factory loaded with extreme for caliber 156-160 grain bullets (SD .328) and these are popular in Sweden for moose hunting.
Another caliber highly regarded for penetration with heavy bullets is the .284/7mm. A 160 grain bullet is the common choice for hunting large game with a 7mm rifle, and for good reason. It has a SD of .283, almost the equal of the 140 grain 6.5mm bullet. Among the popular North American 7's are the 7mm-08 Remington, 7x57 Mauser, .280 Remington, 7mm WSM, 7mm Remington Magnum and 7mm Weatherby Magnum. The standout in terms of rifle and cartridge sales is the 7mm Remington Magnum, the most popular magnum cartridge in the world.
The short action 7mm-08 is factory loaded with bullets weighing up to 150 grains. All of the others can be had with 160 grain or heavier bullets and the 7x57, 7mm Rem. Mag. and 7mm Wby. Mag. are factory loaded with 175 grain bullets offering an extreme .310 SD
From the 7mm's we jump up to the .338's, since none of the common .30, .303 and .32/8mm cartridges meet our basic criteria. The .338's are the medium bore equivalents of the 6.5mm small bores, in that they owe their reputation as superb killing cartridges to the typically high SD of their bullets. Particularly noteworthy in the caliber is the .338 Winchester Magnum, the only medium bore cartridge on the top ten best seller lists and the cartridge that put the caliber on the map.
The popular 225 grain .338 bullets have a SD of .281. 225 grain bullets are commonly factory loaded in all of the .338's from the .338-06 A-Square on up in case capacity. The right 225 grain bullet will suffice for all CXP3 game without being too outlandish for occasional use on CXP2 game.
For maximum penetration on CXP4 game, which is within the capability of the Magnum .338's where legal, a 250 grain bullet (SD .313) is appropriate. This bullet does not shoot as flat as the more popular 225 grain projectiles and would be a poor choice if CXP2 game is also on the menu, but it handily exceeds the highly respected 300 grain, .375 caliber bullet (SD .305) in both sectional density and ballistic coefficient, making .338 the best long range caliber of any of the medium bores.
None of the common .35 caliber bullets achieve a SD of .280 or greater. However, the 9.3mm cartridges can and typically do. Little known in North America, the 9.3mm caliber remains popular in Europe and Africa. Available in factory loaded form in the US are the 9.3x57, 9.3x62, 9.3x64, 9.3x66 (.370 Sako) and 9.3x74R. The 9.3x57 is similar in purpose and application to our .358 Winchester, while the others are intended primarily for CXP3 game and the occasional CXP4 critter. They are the Continental equivalent of the Anglo-American .375's.
The signature bullet weight for the 9.3mm's is 286 grains. This offers an SD of .305, the same as a 300 grain .375 bullet, and it is used for the same purposes. North American reloaders using any of the 9.3mm cartridges might reasonably choose the 270 grain Speer bullet for CXP3 game, which has an SD of .288. Either way, in North America these cartridges are best reserved for hunting moose, bison and the great bears.
That completes our little survey of cartridges. The .375 Magnum and larger calibers that can handle bullets with an SD of .280 and beyond are special purpose cartridges intended primarily for hunting CXP4 game. As such, they are beyond the purview of this article.
Note: All of the cartridges mentioned here are described in detail in articles on the Rifle Cartridges page.
Copyright 2009, 2012 by Chuck Hawks. All rights reserved.