Sunday, October 23, 2011

THE .50 CALIBER MYTH

According to “experts,” a .50 caliber sniper rifle can destroy an airliner. Therefore, civilian ownership of .50 caliber rifles should be banned.

In 2005 CBS News aired a program addressing the “threat” that privately-owned .50s pose to air travel. The onscreen critic was Tom Diaz of the Violence Policy Center. He told CBS, "I just think that there are certain occasions when we say in our society, this product is such a threat to our health and safety, and in this case, our national security, we will not allow it."

The gun-rights side of the subject was provided by firearms maker Ronnie Barrett (no relation—I’ve asked him). Commenting upon his highly successful M82, he stated, "It's a target rifle…a high-end adult recreational toy. Any rifle in the hands of a terrorist is a deadly weapon." That includes airliners hijacked because passengers are prevented from defending themselves.

Apparently the worst-case realistic scenario floated by .50 banners is airplanes sitting on the ramp or taxiing. In fact, military snipers can use .50s on hard targets such as parked aircraft, radar dishes, or vehicles. Put a couple of 700-grainers through a jet engine, and that airplane is grounded pending repairs. But that’s an inconvenience, not a disaster.

Incidentally, rifle shooters (and some gun banners) know that any hunting-caliber round will easily penetrate the aluminum skin of any commercial and many military aircraft—from way out there. The difference is that gun banners are selective in what they tell you.

So, how about hitting an airliner in flight?

The only way to do so would be a plane taking off or landing. Assuming the .50-caliber terrorist got within range (perhaps between a quarter and half a mile) he would need a no-deflection shot for much chance of a hit. But that means positioning oneself directly behind or ahead of the flight path at a metropolitan airport—and firing in a matter of seconds.

A side aspect probably offers better chances for a shooting position. But from 400 to 500 yards, a full-deflection shot on a jetliner landing or climbing at 130 to 150 knots would require a lead of perhaps 100 to 150 feet or more to hit a desired spot—assuming the shooter was fast and accurate with a 30-pound piece of metal.

If anyone has a way to practice that shot, it would be fascinating to observe. First you’d have to rent a 737 or better—starting at about $120 a minute, never mind the return deposit on the airplane. Then you would need a haji jet pilot to fly it around the pattern until your shooter dials in his lead for a given speed and distance.

And incidentally, bargain-basement discount ammo goes for about $3.50 a pop.

Are you starting to see a pattern?

Assuming a hit, what would be the likely result?

We can tell you with some precision: it would be a half-inch diameter hole in an airplane weighing around 35 tons, not counting fuel, which would depend upon takeoff or landing.

Couldn’t that hit kill somebody?

Yes, conceivably it could. But why bother to shoot one or two airline passengers when you can blow up dozens of people with one bomb? Or thousands if you hijack an airliner full of defenseless passengers.

But could a .50 caliber hit destroy the airplane?

No. And here’s why.

During World War II and into the jet age, the standard U.S. fighter aircraft armament was six Browning M2 .50 calibers. They cycled at 800 rpm or more—at least 13 rounds per second. Times six equals 78 rounds for a one-second trigger squeeze. That’s a lot of hefty projectiles starting at 2,800 foot-seconds.

How effective was that armament? Across the board it typically resulted in 60 percent of enemy aircraft hit in air combat assessed as destroyed, though that figure is optimistic. We won’t address those credited as “probables” because their fate is unknowable, but the large majority certainly survived.

Meanwhile, in the Pacific Theater the combined efforts of Army, Navy, and Marine fliers resulted in nearly 1,000 Japanese aircraft damaged in aerial combat. Almost 800 more were damaged in the China-Burma theater. And remember that Japanese design philosophy minimized armor plate and protected fuel tanks.

In the European and Mediterranean theaters, Army Air Force fighters scored nonlethal hits on some 4,000 Axis fighters and bombers.

Over Korea, U.S. Air Force fighters (mostly F-86 Sabres) also had six .50s, firing at a higher cyclic rate than WW II. They damaged nearly 1,000 Communist aircraft—mostly MiG-15 jets.

The foregoing figures total some 6,700 enemy aircraft hosed by multi-gun batteries firing .50 caliber ammunition: ball, tracer, armor-piercing, and/or incendiary.

So: how much damage can be expected from one, two, or maybe five .50 caliber rounds on an airliner?

You can figure it for yourself. It ranges from insignificant on the high end to nonexistent on the low end.

Meanwhile, instead of banning rifles that pose no serious threat, the opponents of personal firearms should look elsewhere. By far the most serious threat to aircraft is the shoulder-mounted antiaircraft missile generically known as MANPADS (man-portable air defense system). The best known are the American Stinger and Soviet-designed SA-7 and later heat-seeking missiles, effective against jet airplanes and helicopters. A generic MANPADS brochure states that it can hit a 700 mph target above 15,000 feet.

When the NATO operation in Libya approached its height, apparently nobody in Brussels or in Washington considered that the late-unlamented Moamar Qadaffi (however his name was spelled) accumulated tons of them. Press accounts noted that some 20,000 disappeared when the rebels seized the colonel’s armories. Perhaps NATO could have prevented or minimized the theft, perhaps not. In any case, failure to do so represents a gigantic Oops that may return to haunt Western frequent fliers for years to come.

Meanwhile, no civilian casualties are known inflicted by privately-owned .50s, and certainly no airliners have been damaged.

However, if anyone wants to address criminal activity involving .50s, recall that under “Fast and Furious” BATFE not only permitted but encouraged dealers to sell them into Mexico, without an export license. Under federal law that’s a felony violation of the Arms Export Control Act and the International Traffic in Arms regulations. Maximum penalty is ten years and $10,000.

Just thought I’d mention it.

5 comments:

  1. Most folks have no idea how thin the skin of a modern passenger jet is. I was a "Sky Marshal" circa 1970, and they took us inside a stripped 747. We had to walk on boards placed acorss the ribs, otherwise we would step through the skin. In fact, we were told a common Bic pen could go right through it.
    However, they also told us that the ventilation system depended on several large exhaust vents, allowing air to escape the body (otherwise your seatmate's perfume would linger). A .38 caliber hole would only cause the vent valve to close a tiny amount. In fact, bullet holes in the skin are of minor importantce, as long as the projectile hits nothing important - like the pilots.

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    1. The "vent" you are talking about is called a schrader valve. The pressurized aircraft cabins always get the same amount of bleed air from the turbines. The pressurization is controlled by how much air is released through the Schrader vale. So you are correct. As the plane climbs the valve opening gets smaller to maintain, usually, an 8000 foot cabin altitude. It would take a LARGE hole in the pressure vessel to cause the cabin to lose pressure. So the myth of a bullet, or even dozens, causing rapid decompression is just that, a myth.

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  2. The .50 Cal BMG round can destroy anything on the planet.

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