Accurate Rifle Cartridges
By Chuck Hawks
Despite the fact that most gun writers, including me, have used the term "accurate cartridge" (as in, "The .308 is an inherently accurate cartridge.") to describe a rifle cartridge, the term is misleading. It is the rifle itself plus the care and precision that went into loading a given cartridge that primarily affect its accuracy. (Leaving aside environmental factors and the ability of the shooter for the purposes of this article.)
The specifics of the cartridge design itself have little to do with real world accuracy, and there is probably no such thing as an inherently accurate hunting cartridge design. Most any hunting cartridge can be very accurate in a good rifle with precisely loaded ammunition, and not so hot in an indifferent rifle with mediocre ammo.
Basically, the case capacity determines the inherent accuracy of any given cartridge, other things (like the rifle) being equal. There is no magic bore size or shoulder angle or head diameter that confers a special level of accuracy on any cartridge design.
This can be observed in the extreme accuracy sport of bench rest shooting. No cartridge using a magnum case, a standard capacity case (.30-06 size), or even a normal short action (.308 size) case can cut the mustard in this exacting game. All of the top bench rest cartridges use small capacity cases. The diminutive .222 Remington was a top bench rest cartridge back in the 1950's, and today it has been superceded by small, even shorter, cases such as the .22 BR Remington, .22 PPC, and 6mm PPC.
And similarly, because relatively small bore calibers are best suited to small cases, the top bench rest calibers are in the .22"-.24" range. .270's, .30's, and 338's need not apply. This in not to say that very accurate bench rest rifles have not been built in calibers like .30-30 and .308 Winchester, because they have, but those are not the calibers that win the matches and set the records.
Let's face it, modern hunting rifles are brilliantly accurate, but they are not in the same class as bench rest rifles. Because of hunting requirements (weight, repeat shot capability, reliability, etc.) they can not be. And hunting rifle ammunition is not, should not, and can not be mass-produced to the same standards of accuracy as bench rest cartridges. For instance, the bench rest shooters who win turn the neck of every case to precisely fit the chamber of the specific rifle for which it is intended.
Since the basic procedures for competitive bench rest rifles and cartridges cannot be followed with rifles and cartridges intended for use in the field, the tiny advantages (if any) conferred by special cartridge design become irrelevant. Thus, as I wrote in the beginning of this article, there are no "accurate cartridges," only accurate rifles and precisely manufactured ammunition.
This can be illustrated by examining an "inherently accurate" cartridge, in this case the .270 Winchester. The .270 has always enjoyed a reputation as an accurate hunting cartridge, and in my experience .270 rifles are indeed usually very accurate. I have found .270 rifles to typically be more accurate out of the box than rifles of identical brand and make chambered for, say, the .30-06 Springfield. Since the .270 Winchester uses the exact same case as the .30-06 Springfield (necked down to handle .277" bullets, of course), the basic cartridge case design clearly has nothing to do with the .270's reputation for accuracy.
I can speculate as to the reasons behind the .270 Winchester's reputation for accuracy. For one thing, the .270 has never been a military cartridge, so there are no surplus rifles of less than commercial standard available to degrade its reputation. For another, the .270 was designed for and has typically been chambered in strong, fully technically developed, bolt action rifles, generally regarded as the most accurate type of sporting rifle.
On the ammunition side, it is no secret that the .270 is an outstanding long range caliber. .270 ammunition has always been loaded to high pressure for high velocity. This requires ammunition manufactured with a high level of quality control, which results in uniform ammunition. Uniform ammunition is accurate ammunition. And again, there is no surplus military ammo to degrade the .270's reputation.
There may also be some subjective factors. The .270 is regarded in the industry as a connoisseur's caliber. It is not only one of the most popular of all hunting cartridges, it is known to be favored by very experienced hunters and those who buy expensive custom made rifles, people whose opinions other shooters respect. The rifle and ammunition companies are aware of this, and they know that their reputation may depend on the performance of their .270 rifles and ammunition a bit more than on most other calibers. Also, the .270 kicks a little less than the .30-06 with bullets of similar sectional density, and a lot less than magnum cartridges with similar trajectory, and lower recoil means better practical accuracy.
For all of these reasons .270 Winchester caliber rifles and ammunition have earned a reputation for excellent accuracy. But you will notice that the "inherent accuracy" of the cartridge was not among those reasons!
Note: The rifle cartridges mentioned in this article are covered in detail in articles that can be found on the Rifle Cartridge Page.
Copyright 2002, 2013 by Chuck Hawks. All rights reserved.