What does the second number mean in a gun's caliber?

Question

I know what the .30 means in .30-06 and .30-30, but what about the 06 and the second 30? In the old West, there was a .44-40 and a .30-40. What's the second number?

Answer 1

There is no consistent system. Once upon a time, in the day of black powder cartridges, it was common to have three numbers, as 45-70-500, designating caliber, powder load and bullet weight. This rapidly broke down. The 44-40 might have held 40 grains of powder and a 200 grain bullet, though a 38 grain powder load seems to have been more usual, but then there was the 38-40, its necked-down sister, which is 40 caliber and the powder load for any load was not 40 grains. And when smokeless powder came on the scene, the system couldn't possibly continue to make sense.
The 30-06 is shorthand for "miltary ball, caliber 30, model of 1906."
The 250 Savage, which actually is most useful with a 100 grain bullet, was originally loaded with an 87 grain bullet in order to obtain a 3000 fps muzzle velocity, unheard of at the time of its introduction, and the caliber was marketed as the 250-3000.
It's common for a cartridge to be necked up or down by wildcatters to make a new cartridge, and the two numbers will refer to both the original and the new calibers. 22-250, for instance, is a very popular varmint cartridge of 22 caliber that was developed by necking down the 250 Savage (250-3000) case.
The British, in addition to driving on the wrong side of the road, tend to do the same thing, but backwards from us. The 450-400-3 1/4" is a 40 (OK, 41, but who's counting?) caliber round based on the 450 BPE case. By the way, there's also a 450-400-3" that, in addition to being a quarter inch shorter, has heavier brass in the typical case, at least in the original loadings.
And then there's the 7mm08, which is a 28 caliber (7mm) round based on the 308 Winchester case.
It's actually kind of entertaining to learn all these names and how they came to be, but maddening if you want to make immediate sense of things.

Answer 2

Good gun question!
Naming is kind of a odd ball process. There is no hard fast rules to it. Manufacters and government make it up as they go along..... In the case of the .30-06. The round started as the .30-03 Government. In the year1903 the Army adopted the New Springfield bolt action to replace the old .30-40 Krags. The .30 was the caliber size while the '03 was the year adopted. The round nose bullet was replaces by the Spitzer type in the year 1906 and be came the .30-06 or .30 government( to denote military use).
Meanwhile the lever action rounds like the 30-30 were made in the black power era and the 2nd number refers to power charge size. Then in the rest of the world they use the metric system. So then you had rounds with names like 7.62x39mm IT's a has bullet and case size in the name.

Answer 3

It all depends on the cartridge. As stated before the 06 stands for 1906 the date of origin. With the older cartridges the second number is probably the powder charge, as is the case with the 30-30 (.30 caliber 30 grains of smokeless powder) and the .44-40 (.44 caliber 40 grains of powder). There is a cartridge called the 250-3000 which stands for 25 caliber 3000 fps, this is more commonly known as 250 savage.

Now metric cartridges are a different animal all together. you'll often her things like 7.62x39 this means 7.62 (.30) caliber and the cartridge is 39mm long.

You'll also often hear cute little names after the numbers like .220 swift, .221 Remington Fireball, .218 bee, .219 Zipper, .22 hornet, and so on, most of these are just marketing ploys but some credit the cartridge creator or company that produced the cartridge.

Answer 4

The second number can mean different things as there is no rule as to what it should indicate. The 06 in 30-06 stands for the year the round was adopted by the US 1906. The 30-06 was actually developed in 1903 and finally revised and accepted in 1906. In the case of the 45-70 the 45 stands for the diameter of the round and the 70 stands for the case length which is generally the situation.

Answer 5

That is a bit of a question. The 30.06 designates the year of origin.
Although the original name is .30 WCF, the -30 in the designation was added to the name by Marlin, who did not want to put the name of rival Winchester on their rifles when they were chambered for the cartridge soon after its introduction. The -30 stands for the standard load of 30 grains of early smokeless powder, which was on par with IMR/DuPont's 3031. Over time Marlin's variation on the name stuck, though ".30 WCF" is also proper.

My guess is you'll find similar naming conventions for many.
it will depend on case size or powder charge.

Answer 6

45-70 Caliber

Answer 7

44-40 Cartridge

Answer 8

Well, about all i know is that the 06 in 30-06 is the year it was develooped. sorry i cant be of more help.