Wednesday, November 2, 2011

Caliber Confusion: Some Myths and Misconceptions About Ammo

Caliber ConfusionBy Jeff Davis
Any time you get more than one person talking about guns you will get disagreements. At the very least. There are many myths, misconceptions, and legends about various guns and ammunition, and it seems like everyone who know anything about firearms considers themselves an expert. One of the problems is that the language of firearms has evolved with few rules, and as a result there is  lot of confusion. This won’t solve everything, but here are some things I’ve learned, when I was looking up other things.
Caliber vs. Gauge
Gauge is a measure of the inside diameter  of a shotgun barrel while caliber generally refers to the diameter measurement of rifle and handgun bullets. Except shotgun slugs (a solid bullet shot from shotguns) retain their gauge designation, and the .410 is the caliber of a small shotgun (and never called a 67-1/2-gauge). The gauge designation was developed hundreds of years ago, before accurate measuring devices allowed for precise, repeatable  measurement.
Caliber refers to the diameter of a bullet, and can be expressed in either metric (7mm) or English (.284) measurements, depending on where it was developed (Europe or the U.S.), or the whims of the marketing department of the company that first designed the bullet.
Numbers Aren’t Always Exact
Remember that just because a number exists, that does not necessarily indicate an exact measurement. The .38 Special and .357 Magnum are both 38-calibers, but the bullet is actually 357-thousandths of an inch in diameter. The .30-30, .30-06, .300 Winchester Magnum, .303 and .308 are all different, non-interchangeable rounds that are all .30-caliber. However, 30-caliber bullets are .308-inch in diameter. I once saw a customer go ballistic (pun intended) because he wanted to hand load for his .30-30, and the clerk gave him bullets that were .308-inch in size. The clerk was right.
Those Other Numbers
So if a .30-30 and a .30-06 are both 30-caliber rounds, that are .308-inch in diameter, why do they have those extra numbers? In the case of the .30-30, it meant that there was originally 30-grains of smokeless powder inside the case. Same with the .45-70. However, in the case of the .30-06, the -06 has nothing to do with powder, but rather that was the year, 1906, that the round was adopted by the U.S. Army as the standard rifle round, to be use with the 1903 Springfield rifle (and don’t ask what the Army used in that rifle between 1903 and 1905). There are other cartridges, such as the .30-378 Weatherby Magnum that is 30-caliber (.308), but it used a necked-down .378 case. And then there are rounds like the 7.62x39 and the 7.62x51, where the 7.62 is the metric equivalent of the .308, but the 39 and 51refer to the length of the case.
Never Assume
A .22 LR (long rifle) is much different from a .220 Swift, a .22-250 or a .22 Hornet. A .300 Winchester Magnum will not work in a .300 Weatherby Magnum, and you can’t buy a spacer to make a .300 Super Short Magnum work in a .300 Short Magnum (someone asked me that once). I was once loudly ridiculed by a friend when I told him I wanted to buy a .44 Magnum rifle, because everyone knew that the .44 Magnum was a handgun cartridge. The joke was on him, as there are a number of rifles chambered to shoot handgun rounds (including the .44), and a few handguns that shoot some rifle cartridges. It’s a big world out there.
Other Language Problems
Language is constantly changing, and the rules can change as popular usage changes. It drives me nuts when a gun’s magazine is called a “clip.” However, I often use the word “bullet” to indicate an individual round or cartridge, even though the bullet is actually just one component of that cartridge. I call revolvers “pistols” which drives my son nuts, but then I sometimes do that on purpose (a revolver is a revolver, but a semi-automatic handgun is more accurately termed a 'pistol'). And then there is tradition. The Army still tells soldiers to “Lock and Load” on the range, which never made sense to me, as we were loading, but not locking. The phrase goes back to the loading procedure of breech-lock rifles two hundred years ago, but caries on to this day.
Why So Many?
Looking through a reloading manual I found bullets with actual diameters of .257, .264 (6.5mm), .277, and .284 (7mm). Do we really need so many bullets that are so similar, but actually different sizes? Well, I don’t need them, but someone does. Ever look to see how many different kinds of mustard are available? I like two kinds, but someone is buying all the other variations. The basic answer is that the bullet diameter is only one variable in the performance of a particular round. The case size, and shape, as well as the kind of powder and primer, all have an effect on the downrange performance.

To each his own.

1 comment:

  1. This post is really too informative to us, good perception of images and good description by which any one can get information what they want to this post.......As for as my thinking is concerned this one is the best post.

    Thanks for sharing such a informative post.
    30-06 ammo