Hey guys,
One thing that has bother me for some time now is bullet calibers, not what they are, but how they affect weapons, for example, if you take a gun and change it to use a bigger or a smaller caliber, how would that affect things like recoil, accuracy and so on?

Another thing I would like to know more about is the term "muzzle velocity", I know what it means but I don't know much on how it effects combat. I would be really glad if someone here could answer me.

2156210

2156210

if you take a gun and change it to use a bigger or a smaller caliber, how would that affect things like recoil, accuracy and so on?

Larger calibers tend to kick more, given a similar size case. Example. .25-06 kicks less than the .30-06, and the .35 Whelen kicks more than the .30-06. All three are based off of the same case. Just different size (and weight) bullets. Heavier bullets kick more for the reason tthat for every reaction, there is an equal and opposite reaction. The bullet accelerates VERY quick, the gun has to move back with an equal amount of energy.

The smaller calibers will most likely have a flatter trajectory, due to the increased velocity of the bullet. This means less drop to compensate for at longer distances, and also, less wind drift.

"muzzle velocity", I know what it means but I don't know much on how it effects combat.

Faster the bullet is traveling, the more energy it has down range. That means, it can carry it's lethality further. Also, the faster it goes, the less bullet drop, wind drift, ext., a shooter has to deal with at equivalent distances. And less lead (how far ahead you aim) for a moving target is needed.

Muzzle Velocity is, quite simply, how fast the bullet is travelling when it leaves the barrel. As elementary physics teaches us, KE=1/2MV^2. Velocity is a larger part of the equation than mass is, and therefore, a higher velocity is generally desired. However, in practice, larger rounds tend to be the longer-ranged ones, as they aren't effected by wind pressures as much.

Please see here your other question.

2156210

if you take a gun and change it to use a bigger or a smaller caliber,

I'd like to make a quick note that for most guns, this is a very difficult or even impossible procedure, although there are some (particularly more modern ones) where the gun is designed to make this relatively easy. Still, it will at least require a change of barrels, and almost always also a major change in the gun's mechanisms.

how would that affect things like recoil, accuracy and so on?

Well, changing the gun's 'caliber', per se, isn't much to go on.
the 7.62x38, 7.62x39, and 7.62x54r, for example, all share exactly the same caliber (7.62mm, approximately .30 cal), but they vary widely in power and all other characteristics.

Caliber only describes the width of a bullet, but the bullet weight and amount of powder also make very important contributions.

While larger calibers usually do imply higher energy, more recoil, and more damaging hits, they don't always do so. A 7mm rifle is much more powerful than a 9mm pistol, and a .30-06 rifle is much more powerful than a .45 ACP pistol.

Another thing I would like to know more about is the term "muzzle velocity", I know what it means but I don't know much on how it effects combat. I would be really glad if someone here could answer me.

A bullet with a higher muzzle velocity travels faster at the moment of being fired.
(Though a lighter bullet will lose its energy sooner than a heavy one -- a heavy, slow bullet may outrun a light, fast one at very long ranges. Of course, a heavy fast one will outrun both.)
A faster bullet will drop due to gravity and drift due to wind less than a slower bullet of the same weight, making them easier to aim (though not technically more accurate, it does make them more accurate in practice).
A faster bullet will require less lead (as others have mentioned): you don't have to aim as far in front of a moving target.
A faster bullet will penetrate better and cause more damage than a slower bullet of the same weight.
(Given equal total energies, a fast, small bullet is better for penetrating armor, while a slow, heavy bullet is better for causing more damage to unarmored targets)

Muzzle velocities over 1100fps or so will be supersonic -- the sound from these will be louder than subsonic bullets, due to the sonic boom from the bullet. In supersonic rounds, the target would get hit, then hear the sound of the gun (the further away, the more delay there will be). In subsonic rounds, the target hears the gunshot first, then gets hit. (That distinction only matters at very long ranges though. At short ranges, the two events happen so close together that they seem to happen at the same time.)

2156210

if you take a gun and change it to use a bigger or a smaller caliber, how would that affect things like recoil, accuracy and so on?

That depends on the round used. For example, the US has several .30 caliber rounds: .30-06 (which is 63mm long) and 7.62x51 NATO being the most recognizable. The Russians have 7.62x54r and 7.62x39 (which is an intermediate cartridge, not a full-sized round like the previous 3). Naturally, longer rounds have more capacity to store powder, but the potency of the powder depends on the round as well. 7.62x51 NATO, despite being shorter than .30-06, is a faster round because it has more modern powders. Even variations of the same round have different charstics, such as the original 5.56x45 NATO issued at the beginning of the Vietnam war and the end.

As far as accuracy and recoil, this depends a lot more on the type of weapon. The M60, a .30 caliber medium machine gun, has recoil comparable to an M16, a .222 caliber assault rifle, so much so that it is often used as a regular rifle by Navy SEALs. Meanwhile the Mosin Nagant 91/30 (also a .30 caliber round) will destroy your shoulder if not held properly.

Another thing I would like to know more about is the term "muzzle velocity", I know what it means but I don't know much on how it effects combat. I would be really glad if someone here could answer me.

The velocity of the round as it exits the barrel. Faster rounds, although slowed by air, are faster than slower rounds. The speed of the round along its path varies wildly based on angle, air pressure, distance traveled, wind, etc. but muzzle velocity is a nice, clean number to make comparisons with.