Sunday, July 4, 2010

Firearm Myths

There are a ton of firearm myths going around, thanks to the movie industry. This post aims to deal with some of them.

1. Some ceramic guns cannot be detected by airport security equipment.

This myth was chiefly spawned by the movie, "Die Hard 2: Die Harder", starring Bruce Willis. In that movie, his character makes a reference to a mythical Glock 7 pistol, which he claims is "a porcelain gun made in Germany, costs more than your month's salary, and is undetectable by metal detectors." First, Glock never made a model 7, their first pistol was the model 17. Second, Glocks are made in Austria, not Germany. While it is true that a Glock has a fair amount of polymer in its frame, it is a dense material that is visible to X-rays. Also, 85% of the Glock is still made of steel. The same facts are true for any other polymer framed pistol as well, not just Glocks. In fact, Mike Papac, the advisor from Cinema Weaponry, that supplied the firearms for the movie, tried his best to talk them out of that scene. In his own words, "I remember when we did that scene, I tried to talk them out of it. There's no such thing as a gun invisible to metal detectors, and there shouldn't be, but they wouldn't budge. They had it written in the scene and that was that."

2. You can explode anything by shooting it

We've all seen this scene in countless movies. Hero shoots at a car's gas tank and it promptly explodes into a huge ball of flame. Hero shoots at an oxygen tank embedded in a shark's mouth and it promptly blows the great fish to kingdom come. Hero shoots at an oil drum and creates a huge fireball that distracts everyone. Hero shoots at a ...., well you get the idea.

Frankly, if cars exploded into huge fireballs with every tiny puncture or sudden impact, all automobile manufacturers would have been buried in lawsuits years ago. The TV show, "Mythbusters", famously showed how wrong this is in real life. In order to get a gas tank to reliably blow by shooting it, you need to light a fire outside the tank to vaporize the gas inside it to a point that the tank over-pressurizes and then shoot it with a special incendiary bullet! Normal copper or steel-jacketed bullets just don't produce enough sparks to light anything reliably. Well, there's an outside chance that that a steel jacketed bullet may produce enough sparks to start a fire, but this is not a reliable method of ignition. There's a reason people developed special incendiary bullets for specialized applications. And they're not usually available outside the military.

3. Bullets cannot penetrate behind car doors

You always see police take cover behind car doors in the movies. First, even bullets from a 9 mm. handgun will penetrate a single car door, provided they don't hit the steel support beams of the car. Rifles will easily penetrate through the body of the car and come out the other side as well. There are plenty of videos available on the net showing how false this myth is.

4. Machine guns have unlimited ammo.

Watch any action movie where people carry machine guns and you'll notice that they keep firing for a very long time. Time for a reality check:

This is a M-16 fired in full-auto mode. A M-16 fires at 700-950 rounds/minute depending on model (according to Wikipedia), which means it fires between 11.67 and 15.83 rounds/second. A standard magazine contains 20 or 30 rounds, depending on model. At that rate of fire, a 30 round magazine will be emptied in approximately 2-3 seconds, which is about how long it took to empty his magazine in the video. Also note that a full combat load for an US infantryman is 7 magazines (i.e. 210 rounds). This means, if the gentleman above was carrying a standard combat load and fired everything in full auto mode, he could comfortably finish firing his entire supply in under two minutes, including unloading and reloading new magazines. Notice how he switches to firing in semi-auto mode in the second half of the video.

The same is true for other assault rifles as well, not just M-16s. AK-47s have fire rate of 600 rounds/minute, which is 10 rounds/second, which means they'll empty a 30 round mag in 3 seconds flat. A FN FAL has a similar rate of fire at 650-700 rounds/minute. This is why some military rifle models (such as the M16A2 and M16A4 models) don't even support full auto mode as an option and only offer single shot and three-round burst modes.

Now think of the scene in any movie, where the bad guys break into a room brandishing weapons in full-auto mode and proceed to fire for like 30+ seconds and break every glass in sight, all without reloading once. Do you think that could happen in real life, now that you've seen the video clip above?

5. Silencers reduce the weapon's loud "bang" to a soft "phut".

This myth is mostly seen in various spy movies, where the hero carries a silenced pistol or assault rifle and all you hear is a soft "phut" sound and someone falls over and the security flunkie standing 20 feet away hears nothing. Hollywood also shows that not only are silencers almost silent, but also any cylindrical object can be used as a silencer (water bottle, bottle filled with socks etc.) So what is the truth here?

The truth is there are multiple sources of noise when a gun is fired:
  1. Noise of the hammer striking the cartridge.
  2. Noise due to the exploding propellant material and hot gases leaving the barrel.
  3. Noise due to the bullet flying through the air (sonic boom, if the bullet is flying supersonic).
  4. Noise due to ejecting the empty cartridge case and cocking the weapon.
  5. Noise due to bullet striking the target.
Of these, #2 and #3 are the primary sources of loud noise from a firearm.

First, let us consider the noise due to the exploding propellant (which could be gunpowder, cordite, smokeless ball powder etc.). It makes a lot of noise, about 140-160 decibels (dB) worth. By comparison, a loud hard rock or heavy metal band tops out at around 115 dB or so (The author has personally watched concerts by AC/DC, Motorhead, Judas Priest and Iron Maiden from close range. AC/DC has reached 130 dB on occasion and Iron Maiden held the record in 1985). A metal tube isn't going to do much to reduce the noise of exploding gunpowder. This is what an average pistol (Glock model 36) with a silencer sounds like:

Interesting side-fact to notice is that the silencer is actually longer than the pistol is. Notice that there is no soft "phut" noise coming out of the pistol. Think you would fail to hear it over 20 feet away? Now that you've heard that one, here's what a typical automatic submachine gun (Heckler & Koch MP-5) with a silencer attached sounds like:

Notice that it sounds nothing like the movies make it out to be. Mind you, this is a weapon that fires smaller pistol ammunition, not full sized rifle ammunition. There's no soft "phut" sound in this video clip either. As with the previous myth, notice how quickly the shooter goes through her 30 round magazine as well.

So now that we've seen that silencers aren't exactly very silent, what are they for then? Well, they do reduce the sound a bit, from 140-160 dB to 130-145 dB or so, with the quietest ones measuring up to 117 dB. This reduction in loudness level makes it more easier to bear, especially when hearing protection is added. They also reduce the recoil force of the weapon. They also alter the sound signature a bit, so the resulting sound doesn't sound exactly like a gunshot (hence, the Finnish expression, "A silencer does not make a marksman silent, but it makes him invisible.") They are also more useful in closed environments, such as inside a building, where the loud sound and flash could disorient the person shooting the weapon. In the case of supersonic bullets, the sound of the bullet breaking the sound barrier often overshadows the sound of the silenced barrel, so it often misdirects people as to where the shooter is.

Since silencers don't actually make a gun silent, the term itself is a misnomer. In fact, the firearms industry prefers that you refer to them as suppressors instead.


  1. The problem is that a gun undetectable by metal sensors is not impossible to produce. It would be ridiculously-difficult to produce such a gun, no doubt, but not impossible to.

    With the best (mechanical) engineering minds, a totally new weapon, used in the same way as any pistol, with a different set of mechanisms, can be produced.

    Who would the gun be for? Such a gun may be issued to government operatives, such as officials' bodyguards, or anti-terrorism squads.

  2. As for rounds, what can I say? As long as there's gunpowder, almost anything hard enough to withstand an explosion can make a round.

    The chamber of the gun mustn't melt from the heat of repeat firing however.

    The final product must also be subjected to various tests, and over a prolonged period of time, say, months, to determine both its safety and userability.

  3. Damn you hollywood//bollywood !

    By the way, what's the average life of a suppressor ?

  4. Jamwal, I'll have a separate article on suppressors later :).

  5. hmmm, it would be intresting to see how a Welrod compairs against a moden supressed rifle/pistol