gun and ammo question?

Question

could someone please explain caliber to me? why is a 30-30 a smaller caliber rifle that a 270, while a 45 caliber pistol is a larger shell than a 38? and then how does a 9 mm figure into this? is it a difference between english and metric system, or what? also, could you add something about how far a given shell will travel and compare that with impact it hits with. does that even relate to caliber of the gun? thanx! jk.

well that don't make no sence then. so a 30 30 is a larger caliber than a 270 but the 270 shell is longer with a larger load, so it's more powerful? why not just make longer 3030 shells?

oh! so the 270 is also more accurate because of the way it's riflled? they don't tell you that part. cool! thanx!

i bet caliber = barell calibration, inside diamater. and the you can adjust the load, length etc....and the reason these guns are popular is they have proven over time to be the most efficient. right? .25, .22, .30-30. .27. etc...i think i see..thanx!

yeah the 30-06 really confused me. thanx for the clarification on that one. i did not know that! thanx.

Answer 1

answering....

The 30-30 in NOT a smaller caliber. The .270 is .27 inch but the 30-30 is .308. The 270 has a longer case therefore it packs more power and powder. Same with the .45 and the .38 it is .45inch and .355 ( they measure the grooves now but used to measure the lands of the rifling back in the day which is .38 inch. The 9mm is .354 inch.

The 9mm versus .38 is a good comparison to start with . You have to realize that case size is a large factor. the standard 9mm round carries a 115 grain ( usually but they make other weights) bullet. There are 7000 grains in one pound. It leaves the muzzle at 1180 ft/s ( feet per second) just over the speed of sound. That's 360 m/s ( meters a second). That generates 356 foot pounds of energy.

The 357 magnum has a much longer case but the same size bullet ( close enough). With a 130 grain bullet( it may be longer but it's still the same bore diameter), it's traveling at over 1400 ft/s and generates 574 foot pounds of energy.

The faster the bullet the less drop there will be at distance. Of course that means recoil increases with bullet speed.

The metrics are usually easier to understand. The 308 winchester is also a standard NATO round. It measures 7.62x51mm.

Answer 2

Simply put, caliber is the approximate diameter of the bullet in hundredths of an inch. I say approx. because a 45 LC and a 45 ACP use different diameter bullets, but the difference is in thousandths of an inch. A 30-30 is an old cartridge dating from the blackpowder era. At the time, it was common to designate a cartridge as caliber - powder charge, hence 30-30 is a 30 caliber bullet with a 30 gr powder charge. A 270 on the other hand is a modern cartridge that is essentially a 30-06 case necked down to 27 caliber.
Yes, 9mm is a metric designation. There are now I think only 3 countries in the world that have not adopted the metric system and the U.S. is one of them. A 9mm is approx. 355 thousandths of an inch in diameter, which would make it a 35 caliber.
As a general rule, the larger the bullet the heavier and the more it will drop due to gravity, but it will also hit harder than a smaller caliber. I say general rule because magnums are an exception to that. The smaller calibers will fly faster and are usually better for extended ranges but don't hit as hard. Again magnums are an exception.
Hope that helps.

Answer 3

There are many systems for measuring cartridges but in the end bigger should not be the issue but which one has better ballistics for the task at hand.

A 30-30 is shorter in over all length than a .270. But the bullet diameter of the 30-30 is greater. The 30-30 like most other calibers involving a dash gets its name from the black powder days. 30-30 = 30 caliber and 30 grains of black powder. 30-40 Krag = 30 caliber and 40 grains of black powder. Following the process I'm sure you can guess how 45-70, 44-40, or 32-20 work.

Metric is interesting and tried to simplify cartridges. The designation for 9mm luger or what you call 9mm would be 9X19. The first number 9 being the approximate diameter of the bullet and 19 being the case length, all in millimeters. A provisional leter "R" is added for rimmed cartridges like 7.62X54R. I still have yet to figure out metric designations for semi-rimmed or belted magnum cartridges.

When you mention 45 versus .38 this again boils down to overal length and bulelt diameter issues. The .45 bullet has greater diameter and is usually heavier where as the .38 is longer.

But there is something even more sinister lurking behind .38 when you look closer. Bullet diameter of the .38 is no where near .38 it is more like .355 The problem is, some pistol calibers are measured by the outside diameter of the neck of the cartidge at the crimp. .38 is one of them as are quite a few .32 calibers. 32 H&R mag is another, it is measured n the neck of the brass rather than bullet diameter.

As to the last part of your question, there is no way to lump all calibers into one rule regarding their effective ranges and their energy retention.

Answer 4

Caliber is based on inches. Millimeters are a different measuring system.

You often see some calibers like, 30-30, 30-06, 45-70

The first set of numbers is the caliber, the second set may refer to the year the bullet or rifle was introduced or the amount of black powder used in the load. The .30-06 is a .30 caliber rifle introduced in 1906 and the .45-70 is an old load with a .45 caliber bullet that was once loaded with 70 grains of black powder.

Europeans use the millimeter to measure the diameter of the bullet (like we do) and sometimes the length of the round. So, you will see something like 7.62x51 for a rifle round, which in the States is a .308 caliber.

Let me confuse you completely. The .380, .38, .357, and 9mm are all projectiles that are about the same size. In fact, if you were careful you could load each of these projectiles into a case and fire them out of one gun. The main difference between the rounds is the length of the case.

Now, is all that about as clear as mud??

Answer 5

The .30-30 refers to the caliber, and the original powder charge of 30 grains of powder, not the length (which happens to be 51.8 mm or 2.0395").

From the caliber, there is no way to know the size of the cartridge. And different cartridges of the same caliber have different lengths, sizes, and power levels. And caliber and power levels do not always co-inside. For example, a very old, and popular rifle cartridge is the .45-70 Government cartridge. It is a .458" diameter bullet, originally charged with 70 grains of blackpowder. While relatively powerful, smaller caliber cartridges such as the .300 Winchester Magnum have far higher velocity, more muzzle-energy, and greater range capability.

Likewise, there are more than one cartridge that use the same caliber, or bore diameter. For example, the .30 M-1 Carbine, .30-30 WCF, .308 Winchester, .30-'06 Springfield, 7.62x39 mm Soviet, .300 Savage, .30-40 Krag, 7.62x54 mmR Moisin-Nagant, .300 Winchester Magnum, .300 H&H Magnum, .300 Weatherby Magnum, .308 Norma Magnum, .300 UltraMag, and .300 Winchester Short Magnum all use .30" bore diameters, but different cartridge case designs and sizes hold different powder charges giving vastly different power levels.

It this perfectly confusing? Not a big surprise. If we could sit down over a pot of coffee or a jug of good bourbon, I could probably clear up some of the confusion, but to do it in writing would take volumes.

Doc

Answer 6

A 30-30 is not smaller than a .270..... the caliber is larger .30 versus .270, the 30 - 30 shell is shorter in length (30 millimeters) versus the .270, so the .270 is more powerful.

A 45 caliber is .45 and a 38 is .38 smaller..... a 9 mm is equal to .354 caliber....

You also have to consider the grain of the projectile, which is the weight .... the heavier the more power it will have.

Answer 7

yes it is a differance between the english and metric system. most calibers are listed in the english system as hundreth's of an inch (25 caliber=1/4 inch) and a 9mm = about a 28 caliber. As far as how far and hard a bullet will travel get complicated as it deals with balistics. Shape of bullet, size of shell (how much powder is pushing it) , grade of powder, and quality of rifling (barrell of gun) .