Gun Mythbusters...

[DunedinDragon]

I get so tired, as I'm sure many of you do, about various gun myths from gun store clerks and firearms instructors. How about we start a thread here busting some of the more common gun myths? I'll start:

MYTH: Don't keep your magazines loaded as it will weaken the springs and cause failures:

TRUTH: Metal fatigue (which springs are made of) is caused when the molecules in the metal create fricton when there is movement in the metal. If the metal is stationary (as in a loaded mag) there is no possible way for it to move and therefore it's "springy-ness" can't be affected.

MYTH: A XX-caliber bullet will knock a person off their feet.

TRUTH: Refer to Newtonian physics regarding action and equal reaction. If a bullet would knock a person off their feet, it would also knock YOU off your feet when you fired it.

MYTH: Bullets rise slightly at the beginning of their trajectory because all barrels are mounted pointing slightly upward.

TRUTH: Bullets rise initially because of the air pressure they create and "ride" on in the same way as an aircraft wing creates a center of low pressure above the wing.

These are all I could think of right off the top of my head. Anyone have any more???

 

[DunedinDragon]

Ooops...thought of another couple of myths:

MYTH: If you shoot an intruder inside your house and he falls dead outside your house, drag him back inside before you call the police.

TRUTH: If you shoot an intruder inside your house it's very likely he will fall dead outside your house unless you happen to get a perfect shot that immediately debilitates his nervous system. Affecting ANY change in the physical evidence is more likely to convict you of a crime than it will exhonerate you.

MYTH: Military ammunition is designed to wound rather than kill.

TRUTH: The military has spent millions of dollars in research over the years trying to find the best ammunition, loads, rifling, etc. for killing as quickly and surely as possible. There has never been a Request For Proposal by the military in seeking to buy firearms which has specified "wounding ability" as a preference. The last thing in the world they want is for a soldier to get "repaired" so they can return to fight some more.

 

[doggscube]

MYTH: Military ammunition is designed to wound rather than kill.


Perhaps this theory is based on the FMJ restriction.

-Jeff

 

[tuckerdog1]

Right off the bat,

I'm sure not an expert in aerodynamics. But the bullet lift thing does not make sense to me. The low air pressure over the top of a wing surface is caused by the curved shape of the top, vs the flat surface of the bottom. A bullet would have the same shape top & bottom, and also be spinning very quickly. So any irregularities in shape, would be nullified by the constant changing of the position of the inconsistancy.

But willing to be shown how I'm incorrect.

Tuckerdog1

 

[Archangel]

I'm with tuckerdog. I think you got your myth / truth backwards on the issue of bullet rise.

 

[DunedinDragon]

http://pages.zdnet.com/remingtonsniper/id12.html

Actually, in doing more research...you're right! I guess that's what I get for believing what I might read on the internet, huh??

 

[marlin.357]

Bullet rise myth

You might also want to research the effetcts of recoil on bullet rise.

 

[boofus]

MYTH: A XX-caliber bullet will knock a person off their feet.

TRUTH: Refer to Newtonian physics regarding action and equal reaction. If a bullet would knock a person off their feet, it would also knock YOU off your feet when you fired it.

Not a myth, do a google search for .477 t-rex. I got no doubts that thing could knock both the shooter and the target onto their butts. The one video where the gun flies out of the shooter's hands and breaks the window behind him is kinda funny.

 

[Gun Wielding Maniac]

MYTH: Bullets rise slightly at the beginning of their trajectory because all barrels are mounted pointing slightly upward.

TRUTH: Bullets rise initially because of the air pressure they create and "ride" on in the same way as an aircraft wing creates a center of low pressure above the wing.

This isnt true.
What happens when a bullet leaves the barrel of a gun is determined by two things. The line of sight through the front and rear sights to the shooter's eye and the center axis through the bore. Bullets do not rise in relation to the center axis of the bore when they leave the barrel, they only fall. However, the line of sight is usually about an inch to 2 1/2 inches above the bore. The goal is to hit the target with a bullet. Now, if the line of sight, which is above the bore, were placed on the target and yet the bullet only falls once it leaves the barrel, how then can the bullet be brought on target?

The barrels are not mounted angled upwards... it is the sights themselves which have to be adjusted to the path of the bullet. By raising or lowering the front or rear sights the line of sight can be made to coincide with the path of the bullet at two places. The first place is when the bullet is rising to meet the line of sight, crosses over and reaches its apogee, the second place is where the bullet is falling and crosses the line of sight again.

The first place where the bullet crosses the line of sight is called the zero. This is why in the military sighting in rifles at 25 meters can give a good approximization of a 300 meter zero.

So, once again, bullets do not rise in relation to the axis of the bore once they leave the barrel, they only rise in relation to the line of sight. It has nothing to do with angled barrels or air pressure currents.

 

[V4Vendetta]

So your saying that leaving 30 round clips fully loaded for periods of time won't harm them?

 

[AJ Dual]

The alloys used in springs, their temper and heat treating, and the number and type of coils they have are designed to have a certain amount of compression or tension applied to them before they fail. This is called the elastic limit.

Compressing or stretching a spring past the elastic limit is known as plastic deformation.

Any engineer worth his or her salt in the past 150 years and probably more, knows how to design things so that springs are never taxed past this point in the normal functioning of whatever device they're used. Before that time, experience and instinct guided them

http://www.findarticles.com/p/articles/mi_m0BTT/is_163_27/ai_99130369

Unloading/relaoding your magazines and rotating ammunition is not a bad idea, but it has more to do with dirt, case deformation, and binding, and nothing to do with the spring taking a "set".

 

[BigFatKen]

myth?

"MYTH: A XX-caliber bullet will knock a person off their feet.

TRUTH: Refer to Newtonian physics regarding action and equal reaction. If a bullet would knock a person off their feet, it would also knock YOU off your feet when you fired it."
**********************************
This does not sound right. A shooter can ready himself and if neccessary place the butt against a rest. I fired plenty of M-79 rounds in a 5 pound weapon. After a couple, I let it kick into a sandbag. Velocity is squared for total energy.

Trap shooters lean into the gun to lessen recoil. They are prepared for the recoil. A perp may be cought off guard.

 

[fletcher]

MYTH: Don't keep your magazines loaded as it will weaken the springs and cause failures:

TRUTH: Metal fatigue (which springs are made of) is caused when the molecules in the metal create fricton when there is movement in the metal. If the metal is stationary (as in a loaded mag) there is no possible way for it to move and therefore it's "springy-ness" can't be affected.

While I agree that you don't have to worry about leaving them loaded (I almost always leave mine loaded), it is possible for a spring to weaken without being fatigued.

Fatigue is due to cyclic loading, and the propagation and arresting of cracks in the metal, and will result in failure after many many cycles. Nothing to really worry about in a modern magazine spring.

However, over time, it is possible, but not likely (due to modern design) for a magazine spring to undergo stress relaxation. Since this goes hand-in-hand with creep, which is only a significant short-term factor at temperatures > ~.5-.7 Tm (melting temp). For plain carbon steels, that's about >1000F. So, unless the spring is in a very warm environment for a number of years, there's really nothing to worry about.


But, I was just clarifying that weakening can take place without fatigue / movement.

 

[nwgunslinger]

MYTH: Military ammunition is designed to wound rather than kill.

I believe that myth started around the time the military switched to the .223 (5.56). We heard that myth all the time in Vietnam and being young and stupid, we believed it. Probably because a FMJ .223 was less than fatal all too often.

 

[Sergeant Sabre]

MYTH: The Geneva Conventions require military powers, including the United States, to use FMJ ammunition

TRUTH: The Geneva Conventions deal with the treatment of war prisoners, so this myth is wrong right off the bat.
The Hague Accords, however, restrict the use of ammunition that causes "undue suffering" when each of the powers engaged are uniformed military combatants. The United States is not subject to this restriction because we were not a party to the Hague Accords. Also, in current context, our opponents are not uniformed military personnel.

We use FMJ because it's cheap.

 

[tellner]

As part of a Technology Assessment course years back I read the OTA's report on the M-16. One of the chief reasons they found for the switch to .223 was to allow soldiers to carry more ammunition. No mention of wounding rather than killing, although they did fault the new round for being less effective.

 

[RevDisk]

MYTH: The Geneva Conventions require military powers, including the United States, to use FMJ ammunition

TRUTH: The Geneva Conventions deal with the treatment of war prisoners, so this myth is wrong right off the bat.
The Hague Accords, however, restrict the use of ammunition that causes "undue suffering" when each of the powers engaged are uniformed military combatants. The United States is not subject to this restriction because we were not a party to the Hague Accords. Also, in current context, our opponents are not uniformed military personnel.

We use FMJ because it's cheap.

We do have that pesky War Crimes provision of the US code.

http://www4.law.cornell.edu/uscode/html/uscode18/usc_sec_18_00002441----000-.html

http://caselaw.lp.findlaw.com/casecode/uscodes/18/parts/i/chapters/118/sections/section_2441.html

 

[Carl N. Brown]

good topic for open discussion

"MYTH: A XX-caliber bullet will knock a person off their feet."
AGRREED:
If a 1 oz 12 ga slug at 1500 feet per second completely transfered
all its energy to a 180 pound target, the 180 pound target would
have a velocity of 0.52 feet per second, rockback but not knockdown.

"TRUTH: Bullets rise initially because of the air pressure they create
and "ride" on in the same way as an aircraft wing creates a center
of low pressure above the wing."
DISAGREE:
A bullet is symetrical and spinning and is not comparable to an aircraft
wing: any "lift" would be neutralized. Bullets do appear to "rise" across
the line of sight due to the relation of line of sight, line of bore and
trajectory:

Complicating this is that if the crown or muzzle is not perpendicular
to the line of bore, the bullet may be biased up, down, left or right.

 

[Jim K]

It is a matter of time, not velocity or bullet weight. A bullet, whether it fully penetrates or not, moves too fast for a mass the size of a man to be affected; people who are shot fall down because they die or are seriously wounded, not because they are "knocked over."

I seem to recall reading that in the "unpleasantness" in 1861-1865, Confederate General (and Episcopal Bishop) Leonidas K. Polk was shot while observing enemy forces from the top of Pine Mountain, GA. I believe reports indicated that his body remained upright for a short period of time before falling down.

The gun was a 20-pdr Parrott rifle. Still think the .45 ACP will knock a man over?

Jim

 

[joab]

So your saying that leaving 30 round clips fully loaded for periods of time won't harm them?

there are reports of magazines being left fully loaded for fifty years with no ill effect

 

[Medusa]

A bullet is symetrical and spinning and is not comparable to an aircraft
wing: any "lift" would be neutralized. Bullets do appear to "rise" across
the line of sight due to the relation of line of sight, line of bore and
trajectory:

Magnus effect does affect the bullet's path, and it does create uplift if conditions are right. http://en.wikipedia.org/wiki/Magnus_effect

A spinning bullet in flight is often subject to a sideways wind. In the simple case of horizontal wind, depending on the direction of rotation, the Magnus effect causes an upward or downward force to act on the projectile, affecting its point of impact. Even in a complete calm, with no sideways wind movement at all, a real bullet will still experience a small sideways wind component. This is due to the fact that real bullets have a yaw motion that causes the nose of the bullet to point in a slightly different direction that the bullet is actually travelling in. This means that the bullet is "skidding" sideways at any given moment, and thus experiences a small sideways wind component.

So don't come to tell me that the bullet's path are affected by line-of-sight/line-of-barrel relation only.

 

[Jim K]

The U.S. is a signatory to the Hague convention; it is not a signatory of the Geneva conventions but has agreed to abide by them.

The problem is that all those conventions are agreements among governments for the conduct of war between nations. They don't include the situation where one combatant group is not representing a nation, but the extremist wing of a religion. For example, the U.S. treated members of the Iraqi and Afghanistan armies as legitimate enemy combatants, regardless of the actual status. But Al Qaeda is not a nation, not a country, not part of any recognized army or armed forces. They abide by no international law or rules, and will not even make such agreements with their enemies, since they cannot deal in any way with infidels except to kill them. They are fanatics, killing everyone, even their supposed friends, in their zeal to rid the world of "infidels" and install a new caliphate to impose Islamic domination of the world.

Jim

 

[CowboyEngr]

I have my own ideas, theories, calculations, proofs, etc., but I think it's clear from the posts/counter posts that the myth is in the eye of the beholder. But of course, some eyes are clearer than others!

Also, never try to convience a man, that is sure about something, he doesn't know what he's talking about!

 

[1KPerDay]

The explanation I've heard for the "wound rather than kill" myth is that if you kill a soldier, you only take one man out of the fight, whereas if you wound him, you take him and at least one other out (him being carried out, fixed up, etc.).

Sounds like doublespeak to me.

 

[AndyC]

So don't come to tell me that the bullet's path are affected by line-of-sight/line-of-barrel relation only.

I'm sure that Uranus, black holes and other heavenly bodies have a gravitational effect on bullets too, but for all practical purposes, I'm going to presume that their effects on a projectile are negligible.

The Magnus Effect aka spin-drift has to do with horizontal drift, it has no effect on a projectile crossing of the line-of-sight in the vertical component - which is what the guys were discussing before you stuck your oar in. I'm not sure where you got your attitude of "Don't come to tell me...." but obviously you know everything.