why is the ammo in guns measured in mm , and also calibers? why can't they all be uniform ,it is very confusin

Answer 1

I agree with you, it can be confusing. Originally, firearms made in europe came in Metric measurements. IE: 9mm etc.
In the U.S. firearms were measure in sae or "standard" measurements like .357 magnum etc. This most commonly referred to the actual diameter of the projectile. Then to make it even more difficult, you add in the shotgun class of firearms which are measured by "gauge", IE: 10 gauge, 12 gause etc. But even more strange, the larger the "Gauge" the smaller the actual diameter of the shotguns barrel. IE: a 10 gauge is larger than a 12 gauge, which is larger than a 20 gauge etc.
It's enough to drive you looney trying to keep up.

Answer 2

The real answer is because you can actually name a cartridge about anything you want as long as the measurement relates to something, or is close enough.

For example a .303 rifle uses a .311" bullet because it uses a different measurement than the ones everyone here has mentioned. In that it measures the inner bore diametre from the lands(top of the rifling) rather than the grooves(the hollows of where the rifling is cut into the bore).


On the other hand a "460 weatherby" relates to no measurement at all since it uses a .458 bullet but its close enough and 460 was just a catchier brand name since there was already a .458 out there called the 458 Winchester.

A 50 cal handgun uses a 50 cal bullet, but the 50Cal rifle uses a .51 cal bullet. A

There are many more examples and in Europe they have the same thing happening with their calibres in mm.

basically you invent a calibre you call it what you want. That is what wildcatters(inventors) do.

Answer 3

Americans for the most part actually use the "English" system of measurement. (pounds, feet, inches, caliber)

Most English-speaking countries, former colonies of the UK and many of the countries they traded with did not abandon this age-old system until the Socialist running these countries bowed to international pressure to conform in the 1960s.

The US has stubbornly stuck to the old system, but when you are the largest economy in the world you pretty much do what you want to do, and the Americans have chosen to keep the old system around for a while. We are adopting more and more metric measurements, but in our own good time.

The system they adopted was the scientific-based Metric system, which includes measuring bore size in Millimeters (mm).

In order to standardize with NATO and other allies armies, our US military has actually used the metric system since the 1960s as well.

As was said, people that develop cartridges in different calibers have a lot of leeway in naming their products.

Answer 4

"Caliber" is the most common notation of a bullet's diameter size in the U.S., being measured in inches, while "Millimeter" is most common in Europe and Asia. But, I think you knew that already. The U.S. is slowly moving towards the European method of using "Millimeter", though. Of course, the larger the diameter, the heavier the bullet and the more stopping power it has, generally speaking.

Look at it this way: A 9mm bullet is the same diameter size as a .354 cal bullet. If you are "confused" by mm versus cal, just convert the .XXX cal measurement into millimeters, or the other way 'round. One rifle I once had was an Arisaka 7.2mm (or was that one 6.5mm?); in U.S. caliber measurements it is .283 cal (or .256 cal, for the other one).

Using the formula, the .45 cal would be 11.43mm, and the .50 cal would be 12.7mm.....which makes them true monsters in Europe.

Answer 5

Hi Linda. Traditionally we use American calibration in the USA. Overseas the millimeter measurement is used. To convert from US ca liberation to mm divide by 4; thus a .40 S & W becomes a 10mm (in the case of the S & W it beomes a 10mm 'short' to differentiate it from the magnum class 10mm). To convert mm to US calibration simply multiply by 4. A 6mm becomes a 24 caliber.

And you are correct, it IS confusing!

Best.

H

Answer 6

It's no different than women.

In the US, a well-endowed woman might wear a size 38 bra. A women in Europe with a similar physique might wear a size 96 or 98.

An M-16 uses English measure, while an AK-47 uses metric.

Answer 7

SIMPLE ANSWER: A 9mmX.04= .360 approximately. In reality the 9mm is an industry standard of .355 (of an inch)
A 7mm is a .285 " and so on. It's just metric to english conversion.

Answer 8

Well, the majority of the world measures "things" using the metric system. This is most likely why ammo is measured in mm. Caliber is an actual measurement of the inside diameter of the bore of a weapon. So it is actually the "correct" way of measuring the diameter of the bore of your weapon.

Answer 9

Because some countries can't get with the times. The metric system is superior in more ways than one.

Answer 10

Simple question, simple answer. Different countries use different measuring systems.