Episode 64: More Myths Revisited

Air Date: October 25, 2006

SPINOFF: A sword can cut a machine gun in two. (From special 9)


A machine gun barrel cannot be sliced in two using a sword. Using the barrel from a .30 caliber Browning machine gun, the team heated the barrel until it was red hot and struck it with the sword machine. Even with the barrel red hot, the sword could only make a small gouge in the barrel. What further disproved the myth was the fact that the barrel’s outer heat-dissipating shroud was removed and the machine was swinging the sword with power that significantly exceeded a normal human’s capabilities. The team then rapidly heated and cooled the barrel to make it more brittle, but when hit by the sword, it shattered instead of being cut. Finally, the team tried to cut a thinner Thompson submachine gun barrel, but only managed to bend it, proving that a sword cannot cut a gun barrel in two.

SPINOFF: Bracing a windshield can keep it from shattering. (From episode 58)


Bracing a window with a hand was unsuccessful in preventing a window from being shattered by a rock or a fired BB.

REVISITED: A hybrid rocket can be made out of salami. (From episode 51)


Using Salami as a rocket fuel can create high amounts of thrust with the right nozzle. Readings from the force gauge proved that salami did in fact generate much more thrust than just the released nitrous oxide gas alone, though they do admit that the NOX output alone could’ve launched the rocket, as may have been the case with the original launch.

REVISITED: It is more fuel efficient to drive your pick-up truck with its tailgate down, rather than up. (From episode 43)


Using a calibrated fuel flow gauge, Adam and Jamie first re-busted the tailgate up vs. down myth, then went on to test various other truck configurations (hard top, mesh tailgate, no tailgate).

SPINOFF: A plastic mesh tailgate provides superior fuel efficiency compared to the standard metal tailgate. (From episode 22)


Again using a calibrated fuel flow gauge, Adam and Jamie proved that the mesh was the most efficient way to configure a pickup truck.


  1. jamoecw says:

    i noticed while watching this one that the sword machine was triing to apply force along its point rather than cut. cutting is caused by friction along the edge, not simply the force behind the sword. pressing the blade against the barrel and sliding the blade will produce much better results (doubtful it will cut through the barrel through).

  2. Gerald says:

    My car, a European standard model Peugeot 206sw 1.4 HDi does 45 miles per gallon (US gallon) at 55mph (measured).

    Jamies pick-up does 11 miles per gallon
    (5 gallons per hour at 55mph).

    Do all US vehicles have such appalling fuel consumption? (and consequently very high global warming greenhouse gas emissions?)

    • MSpears says:

      No. In the U.S., starting 2011, vehicles are required to get a certain MPG based on the vehicle’s “footprint” (which is determined by multiplying its wheelbase by its average track width). Thus, a 2012 Honda Fit with a footprint of 40 square meters must achieve 36 miles per US gallon, while a Ford F-150, with its larger footprint, must achieve 22 miles per US gallon.

      However, cars and light-duty trucks are supposed to achieve 35.5 miles per gallon by 2016, and 54.5 miles per gallon by 2025. Even after their first overhaul in 30 years, though, there is some debate over the CAFE (Corporate Average Fuel Economy) regulations, so this might change.

      And as Ed says, Catalytic Converters are required in the U.S., to reduce air pollution. Unfortunately, older converters also reduce fuel efficiency (in general, the newer the converter is, the less effect it has on the vehicle’s effeciency, because of new technologies being used in new converters.)

    • gg burger says:

      jamie is eiter a moron on mpg or you misunder stood the question 90% of trucks will get 10mpg in extremely bad worn out engine conditions pre-obd2 350sbc up to 30mpg with 2barl carb std bore and stroke

  3. Ed says:

    Gerald, your car must not have a catalytic converter. Do ALL non US vehicles pollute the environment as much as yours?


  4. Josh says:

    I was wondering what the science is behind why the mesh tailgate is the best for fuel efficiency?

    Plus my Honda made here in the US is around 35 highway..

  5. Haddock says:

    Iam not sure but was that Katana a original one? I think not, it was just a cheap replica. The real ones are to expensive (more than 5k $) for using in a test.
    In my opinion a the results would be different if a real katana would be used.
    Check out this video: Katana vs. machine gun. A Katana is able to cut 7! bullets before being broken….

    (sry for bad english:)

    • LazyLemming says:

      The japanese were years ahead in sword manufacturing technique. The ancient masters made incredible blades.

      And yet, they are nowhere NEAR as sharp or strong as legends make them out to be. Katana are by nature no sharper or stronger than other blades, other than the fact the Japanese smiths developed smithing techniques faster than the western world.

      Notice how the Katana actually chipped and broke with each machine gun shot? Now consider that the bullets ARE FAR SOFTER than the barrel of a gun. That’s intentional.

      If the sword struck the gun with the same force, the blade would similarly chip, and thus would be attempting to cut with a dull edge.

      It will never happen people. The ancient sword masters were legendary for their time, but they weren’t magic.

      • gg burger says:

        there is a 1919 that the barel and shroud got cut trou by a jap comander during wwii on film the barel was white hot at lest the kodak could not get very good picture of it gunner was killed the ast gunner escaped he reported they conected crates of belts and fired so many round the barel shroud glowed like the sun in the dark the sword was damaged and captured it was an antiq even. then the jap died by his own hand suicide

  6. Ali says:

    I also have a complaint whether the sword used was a Katana or not, it looked like a European sword to me, katanas are no ordinary swords, they have a carbon core and a special metal called “tamahagni” as the cutting end this metal is only found in Japan & is made from a special kind of soil.

  7. RealityCheck says:

    Hey RaisnCain, got any visible PROOF to dispute your belief that a sword can cut a machine gun?

    Your word-and belief against one documented test to show SOMETHING.

    Swords can’t just cut anything on the planet-get over yourself already. And a Jedi is as fictional as your belief…talk about poor reasoning.

  8. Chris says:

    You have a point RaisnCain. It is in fact scientific law that nothing can in fact be completely disproven. However, until the mythbusters happen to attain the services of a mythic or mythically powered swordsmen, and the producers decide to cough up the money for an authentic, traditionally made katana, I’m afraid we will have to settle for the current findings.

  9. Chris says:

    And the sword cutting bullets, while cool, I am still not convinced. I do not know the force exerted by the bullet at the point of impact, but I doubt it is something a human could do. Also, bullets are a heck of a lot softer than machine gun barrels, and you saw what happened to the sword edge when it broke a bullet. Finally, it did not appear to actually slice the bullet, the bullet appeared to fragment.

  10. TOM says:


  11. Lee Barratt says:

    I work with glass and have done so for over 13 years. I know that placing your hand against the windshield might actually make it break easier, i notice that they never tested this using their pellet gun.
    We manufacture glass and know that when no force is behind the glass or when its in a window, the glass actually flexes more as to when its say on a flat surface like a table etc and hit with a hammer, it will break a lot more easier.

    Thanks Lee.

  12. Why does everyone on this site keep saying that a “scientific law” says things can’t be disproved? There is no such “law” and things can be disproved. One way to disprove a proposition or statement is to provide a counterexample and the mythbusters do a lot of that. The “scientific law” that you are referring to is called the scientific method and it is a method according to which hypotheses are proposed and are then either rejected or not rejected.

  13. De Wet says:

    A hybrid rocket can be made out of salami, good in a controlled environment, when you guys go out to the desert where you do your entire rocket testing, could it be possible to launch one or two out here to get the real affect of what the myth is/was all about.

    Great results in your chamber, I thing the results will be spectacular when launched outside.

    Thanks SA

  14. joe says:

    Tailgate myth

    Mythbusters are dopes. Fuel injection pushes fuel through the fuel line at a constant rate. The engine is injected with the fuel it needs and the rest of the fuel is returned to the gas tank through a return line. They need to measure the difference in fuel through the main line and return line to see how much gets burned.

  15. Justin says:

    the reason for cutting with the tip up the katana blade is that is the only part of the blade that is actually ever sharpened. the rest of the blade is kept slightly dulled as a sharpened edge becomes to brittle to apply along the whole blade. instead the Japanese relied on the softer backside metal to provide both a cushion that helped to prevent the blade from breaking and a slightly elastic force which aided in forcing the “blade” through it’s target. properly sharpened, it becomes gradually sparper until the sharpest point at the tip, which allows it to leave an incredibly clean cut with no tool marks.

    the only part of the blade meant for any impact/cutting is the final quarter of the blade, the rest is there to absorb impact and redistribute some of the force of the impact back to the tip so as to aid it in cutting/forcing its way through things.

  16. Takekaze says:

    Ali, you’re wrong. First of, it’s spelled “tamahagane”, secondly swords with that steel are extremely expensive (only an idiot would use it for such a test) because the raw material is extremely rare, thirdly katana don’t have a carbon core (it’s a mixture of different steels, more flexible inside than outside).

    Justin, you don’t cut with the tip, you cut with the whole sharpened blade (sharpened only on one side, of course). That sharp part IS sharp.I want to see anyone doing iaido by just cutting with the tip. It wouldn’t work. The backside of the blade is used for blocking in ken-jutsu (they can block with the sharp side in Japanese movies, because the blades there are made of plastic). A good sword polisher these days sharpens the whole edge (there’s one who ends up using a grindstone smaller than his thumb for the last step, but of course, nobody would use such a sword for such an experiment, that would be a horrible waste)

    The problem with the setup, as far as I remember, was that a robotic arm can not, under no circumstance, match the skills of a ken-jutsu instructor (and those are far and few outside of Japan, good luck finding one who knows what he’s talking about). Thus the experiment is flawed to begin with.

    I doubt that a robotic arm can even cut properly through straw.

  17. Ken says:

    I saw this ‘myth’ the first time and immediately caught the error. Then they revisited it and made the exact same error.

    My understanding of the myth is a USMC machine gunner experienced a Samurai swordsman cutting his gun barrel in half during the Pacific phase of WW2.

    Several thoughts lead to a plausible conclusion regarding the myth. The US Army, with the exception of the Philippine Islands, had very little role in the Pacific phase of the war. By command decision most of the fighting in the Pacific was done by the Marines. So that part is plausible. Then we come to the weapons which is where I believe Myth Busters were led astray by Hollywood. Myth Busters chose a Browning designed air cooled 1919 machine gun as their test weapon. In the early days of the conflict there was a real shortage of those amongst the Marines. They had plenty of the Browning water cooled versions, but they weren’t suited for mobility and island hopping.

    What the USMC had in their inventory and what saw a lot of Pacific action was an assortment of pistols, some (borrowed from the US Post Office) Thompsons, the Johnson M1941 machine gun (MG) and 1903 and 1917 rifles and (a precious few of) the Johnson 1941 rifle. You can find a picture of the Johnson MG at http://en.wikipedia.org/wiki/M1941_Johnson_machine_gun and some basic info. Very few of these survived the war (I believe most of ours were lend-leased to Venezuela after WWII) in private hands, so when Hollywood makes a WW2 movie showing our Marines they typically give them left over Army weapons such as Browning 1919s, Garands and BARs. A false reality. They didn’t get those goodies until much later in the war. I believe the Myth Busters fell into this Hollywood inaccuracy trap.

    Yes the Browning 1919 MG has a heavy thick barrel and even yellow hot the barrel would be hard to cut with a sword. And there is a full length ventilated steel jacket surrounding the barrel which the sword would also have to cut through. Neither of these is true of the Johnson.MG as used by the USMC.

    The Johnson MG used basically the same thin barrel as the Johnson 1941 rifle. You can find more info on that at http://en.wikipedia.org/wiki/M1941_Johnson_rifle . That steel is a LOT thinner than the barrel of a Browning 1919. The Johnson was used by the Marines in many of the early island battles. The fact that it was a Johnson also explains the mystery of how a swordsman could get close enough to attack the machine gunner. The Browning was fed by a large ammo belt. When facing a Browning 1919 charging foot soldiers were usually mowed down long before they got close enough to even think about swinging a sword. Conversely, the Johnson was fed by a 30 round stick magazine which allowed attackers to rise up and continue every 30 shots, and it didn’t like either sand or mud. One thing those islands had lots of was sand and mud. It is not at all inconceivable to me that some of a few hundred charging Japanese soldiers would make it to a Johnson gunner who had to stop shooting for a few seconds every 30 shots while he inserted a new magazine, nor is it inconceivable to me that the Marine would soon be fighting hand to hand as so many found themselves doing in those early island battles. Now we are down to the test.

    Please re-run the sword test, but this time do it a little more accurately. Continue to use a properly tempered sword (even the cheaper Japanese NCO swords had decent steel and reasonable tempering), but please use a Johnson MG barrel. I recognize that this might cost a little more since they are rarer. Alternatively, you could find an original Johnson MG (there are a (very) few in private hands), measure it’s barrel, then find or machine a .30 caliber barrel of similar dimensions.

    • Bill says:

      I’m sure the men of the 6th and 8th Armies would dispute that they had little role in the Pacific War, having made more than 60 amphib landings….

  18. Kirk says:

    Did anyone notice in the re-visited Salami rocket episode that they kept incorrectly referring to Nitrous as NOx or NO2? Irritating…

  19. ken says:

    Silly waste of time test. The USMC used Johnson MGs in the early Pacific War, not air-cooled Brownings. They got the Browning much later in the war. The Johnson had a really thin barrel and the sword may indeed cut it.

  20. Reginhild says:

    Truck tailgate tests only partially correct.

    Check the full scientific tests by SEMA and SAE. There are variables to consider on the tailgate, mesh, and tonneau testing such as bed length.

    SAE found that 8 ft beds can benefit from tailgate down but not off. They also found that crosswinds make a difference.

    Both SEMA and SAE testing found that tonneaus improve aerodynamics. Reduction in drag with a tonneau has increasing effect between 40 and 65 mph (beneficial effect remains fairly constant above 65 mph) but little to no effect below 40 mph.

  21. Reginhild says:

    P.S.: SAE and SEMA tests did show that typically tailgate down or off is bad. The SAE testing also showed that the mesh tailgate had the worst effect on aerodynamics – the opposite of Mythbuster results.

    I’m going to have to look into joe’s comment above. Did Mythbusters incorrectly measure fuel consumption?

  22. Elijah B. says:

    One thing I still wanted to see in the Salami Rocket Revisit, and that wasn’t shown, was an inspection of the cylinder to ensure that the salami had actually been consumed in the firing. If we had seen that there was still a salami in the cylinder then it would be easily established the test was a failure; likewise, if the salami had been consumed the myth would have been confirmed in a way that would satisfy everyone. The results from the force gauge are not sufficient on there own.

    Another good test would have been with the chemical alone that is in the salami that is supposed to be the active ingredient that does the reacting.

    If my suspicion is correct and that the salami was still not consumed in the rocket firing revisit, then a new design for the rocket, with a more definite smoldering of the salami established before the later release of Nitrous Oxide in a more restricted flow would do much to remove all doubt about their results.

    Instead of complaining when people point out errors in their methodology and implying that fans are a bunch of whingers, the Mythbusters would do well to think through more of their possible errors. To paraphrase an old saying, ‘Scientific testing not only has to be done, but must be seen to be done’. Anticipating the questions people will ask afterward would save them a lot of messing about with revisits.

    Personally, I don’t believe that the salami was actually consumed in the firing (remember, the cylinder wasn’t inspected on screen to see if the salami was still there, or even partly consumed), because there is too much water content in a salami to sustain the burning or smoldering necessary without first being pre-dried. If this myth is ever revisited they really need to show an inspection of the cylinder to remove ALL doubt.

  23. Aaron B. says:

    The fact that the salami was not consumed is evident by the fact that it was spread around the area where they did the test. My personal theory is that they decreased the nozzle size and increased the pressure inside the cylinder. Propulsion would be increased by the increase in pressure, but it simply forces bits of salami out the nozzle.

    AN interesting experiment would be to heat dried salami in a chamber and see if you get a combustible material from it. Then use that material to fuel a small rocket.

  24. Ed says:

    It seems this revisit may need more revisiting. When the mythbusters decided to reduce the size of the nozzle, they needed to do additional control tests with ONLY N20. So that they are comparing apples to apples. You have say 3000psi in that tank, if you blow it out through a 1 inch opening or a 3/8″ opening you will get a significant difference in thrust. (Think of your garden hose, you have consistent pressure from your plumbing, with an open hose there is no noticeable reverse thrust on the hose, then restrict it with your thumb and notice the difference)

    Like others, i’m not convinced the salami was burning at all, rather by reducing the nozzle size they were only increasing the thrust from the N2O

  25. bingo says:

    Gerald’s car would have a catalitic converter, all new european cars have been fitted with them since the early 90’s.

    So NO European cars don’t pollute anywhere near as much as the rubbish the US sells. In this case its around 75% less.

    More :sarcasm:

  26. mike says:

    However Geralds car cannot haul or tow anything like the mythbusters truck can.

  27. Jack Rowe says:

    They should have tried a Moro Kris or Filipino Kris. Accounts from Filipino-American war states that a Moro wielded his Kris easily cuts a Springfield rifle barrel in half.

    • Bill says:

      They M1903 was not in service in that war.

  28. Dart says:

    Nope…they made a fatal mistake…you cannot swing a samurai sword like a baseball bat..It is NOT a machete…the curve of a samurai sword is not only due to the natural curvature of the blade due to the thicker portion on the topside it is also CRITICAL when making the cut..that is why the handle is so long. You have to pull in on the lower portion of the handle while pushing out near the upper portion to properly utilize the cutting power of the blade…otherwise you’re just a hack…literally…

  29. Dart says:

    I have samurai swords and use them…I know this to be true. It’s well known..it’s called “bringing down the mountain”

  30. Dart says:

    Quite frankly I believe a steel sword can cut a lead bullet…that’s just a no brainer…like the airplane takeoff one…And yes, I do believe an ancient japanese sword folded 26,000 times interlayed with carbon could cut a mass produced army weapon barrel.

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