-dash versus /slash

[BoogieMan]

What exactly does the - or / stand for in calibers?
Ex: 30-30, 30-06 -vs- 45/70
Can it be used interchangeably?

[Shootest]

The 30-30 stands for 30 caliber with 30 grains of powder, the - keeps people from calling it three thousand thirty. The 30-06 stands for 30 caliber adopted by the US in 1906, and so on and so on. - or / doesn’t really make any difference, just the way it has been done for so long.

[Doyle]

Most "number set" calibers always use a dash. There are a few oddballs that are normally seen with the slash (like the 45/70).

[Tom Servo]

As others have mentioned, they're conventions, but not standards. One of the confusing things about ammunition development has been the lack of standards.

As Shootest pointed out, the suffixes can mean one of several things. That said, it might confuse some folks to refer to .30/06 or .45-70, but we'd probably know what the speaker meant.

[44 AMP]

The traditional, normal, and preferred method is to use the dash between numbers. Don't know where or when the slash started being used, but it wouldn't surprise me if it were a result of the computer age.

The original designation (name) of the early cartridges was completely random, dependent only on the maker's desires. Usually included caliber (roughly) and the maker or designer's name.

Shortly afterwards, a system was developed using the caliber, powder charge, and bullet weight. Thus we find the .45-70-500 as well as the .45-70-405. Both the same round, but with different bullet weights.

In popular adoption, this was generally shortened to just the caliber and powder charge. This system stayed in general use until the advent of smokeless powder ammo, and of course, older rounds retained their names.

Not every blackpowder round got a name with two (or more) sets of numbers, but most did. A few smokeless rounds also got names with double sets of numbers, to capitalize on the familiar.

Exception to this is the .30-06 (and the lesser known .30-03) where the second set of numbers stands for the year of military adoption, not the powder change weight.

[DaleA]

Internet dictionary:
arcane - known or knowable only to the initiate : secret, mysterious, obscure.

Never had much use for the word until I got into firearms.

(But heck, if it were logical then ANYBODY could do it.)

[carguychris]

Shortly afterwards, a system was developed using the caliber, powder charge, and bullet weight... In popular adoption, this was generally shortened to just the caliber and powder charge... Not every blackpowder round got a name with two (or more) sets of numbers, but most did. A few smokeless rounds also got names with double sets of numbers, to capitalize on the familiar.

While 44 AMP is basically correct here, I would like to stress that not all of the late black-powder era cartridge numbers actually mean what we think they should.

Notably, the .38-40 Winchester cartridge uses a 0.401"-caliber bullet, which would conventionally make it a nominally .41-caliber cartridge. It's an exception from the general rule that so-called .38-caliber cartridges fire 0.357" (or 9mm) caliber bullets.

Arcane indeed.

[Armorer-at-Law]

In at least some cases, the slash is used in a trademark or model name, as opposed to a caliber. Ruger 10/22. Some may start as a trademark and then become generic over time. But there is no convention that I am aware of for one or the other.

[Aguila Blanca]

Originally Posted by carguychris

While 44 AMP is basically correct here, I would like to stress that not all of the late black-powder era cartridge numbers actually mean what we think they should.

Notably, the .38-40 Winchester cartridge uses a 0.401"-caliber bullet, which would conventionally make it a nominally .41-caliber cartridge. It's an exception from the general rule that so-called .38-caliber cartridges fire 0.357" (or 9mm) caliber bullets.

It has nothing to do with what we think they "should" mean. It matters that we know what they DO mean. In the case you cite, the "caliber" is the bore diameter, not the groove diameter. That was often the case with older ('historic") ammunition designations.

Why, for example, can you slap a conversion cylinder into a .44 caliber black powder revolver and shoot .45 caliber ammunition (with an actual bullet diameter of .452 inches)? Because the .44 designated the bore diameter, while the newer .45 designates the diameter at the grooves. .44 caliber cartridge ammo has a bullet diameter of .427 inches (or so).

And, of course, then there are those "calibers" that were designated based on the case rather than the bullet. Both .38 Special and .357 Magnum take the same diameter bullet, they just got named on the basis of a different criterion.

[BoogieMan]

So what your saying in a nutshell is "you have to know to know"?
I didnt even get into pistol cartridges and shotshell. I guess for the most part pistol cartridges make sense. Basic diameter and the inventors (loosely used) name. .454 Casul, 45 Scholfield, 45 Long Colt, etc...
I deal with standards all day in the machining industry. Cant help but wonder why the ammo/gun industry hasnt adopted similar standards considering the possible consequences of not following them. Like putting a Mag load in a Special case.

[gunloony]

So what your saying in a nutshell is "you have to know to know"?
...

Bullseye!
Then when you come across things like 7mm - 08 and 250-3000 you won't be confused. Maybe.

[44 AMP]

The confusing (to the uninitiated) plethora of cartridge names and the relationship between those names and the actual measurements of the cartridge are the result of the un-regulated free market, particularly in the later 19th century.

Cartridges were designed by individuals, or gun company teams, or by government design boards, and named what ever the designer thought was either appropriate, or what was most marketable.

There was a huge rivalry between gun makers, and for many years, some companies would not chamber their guns in another company's cartridge. They would create their own cartridge instead, even ones with virtually identical performance.

Other gun makers would chamber their guns for everything they could.

The caliber designation in a cartridge name bears a relationship to the size of the hole in the barrel. But it is not necessarily a direct relationship. For instance, a .30 caliber rifle is going to have a .3" hole in the barrel. But it might be called a .30, or a .300, or a .308, or a 7.62mm, depending on which measurement is used.

European's favor their system, the British use another, the US today has a more or less standard in use, but its done by common agreement, not govermental regulations. Trade Marks, patents, copyrights, etc, of course all apply.

And when you get into late 19th and early 20th century handgun cartridges it can get really confusing. There are several (obsolete) rounds with either nearly identical names but different dimensions (like the .38 S&W and the .38 S&W Special) and rounds with identical dimensions, but called a Colt when loaded with one style of bullet and a S&W when loade with another style.

And there is more. Whole books have been written about cartridge names and histories. Cartridges of the World is usually considered a pretty good reference, but not infallible.

[Aguila Blanca]

If you're willing to look for it, SAAMI now has their cartridge and chamber dimensional data available on their web site. Before I knew that, I had bookmarked Steve's Pages for his repository of cartridge dimensions.

http://stevespages.com/page8d.htm

[Bart Noir]

Don't know where or when the slash started being used, but it wouldn't surprise me if it were a result of the computer age.

You are off by a little over a century

I have seen pictures in books which were advertisements from the 1870s or 1880s. They sometimes used labels like .44/100 or .45/100 and I just had to ask on a CAS forum.

Seems those meant 44 hundredths (as in .44) etc. Some confusion comes from the fact that there actually was a .45-100 cartridge used in the Sharps to ventilate bison.

Bart Noir
Who tried to find such an illustration online for this response. Another failure he has to deal with.