The invention militia: amateur engineers are asking what they can do for the Pentagon.

• Author: Ackerman, Spencer
• Position: 10 MILES SQUARE

On a recent, chilly day in upstate New York, I found myself riding shotgun in a black Chevy Trailblazer with a small arsenal of assault weapons in the trunk. The driver, Dave Warren, a 39-year-old Vietnamese-born ex-Marine and veteran of Desert Storm, was a man on a mission. An inventor and an engineer for a Connecticut security company; Warren had devised a lightweight vehicle armor he thinks will better protect Humvees from Iraqi insurgents armed with Kalashnikovs and homemade bombs than the steel currently used to belatedly up-armor the vehicles. He's currently lobbying to have it reviewed by the Pentagon.

After we parked at a Saugerties firing range, Warren unpacked his M-14, 12-gauge shotgun, and AK-47--the insurgent assault rifle of choice--then hauled out the experimental armor, which he calls Magmacore. It was a two-inch thick panel about a foot in length and width. Despite weighing 18 pounds or so, it didn't look too sturdy. Its white coating was slathered on, giving it the appearance of runny plaster; while not gummy; the panel flexed ever so slightly when squeezed. Imagine a giant, sugar-glazed Rice Krispies Treat. Not exactly what you imagine you'd want standing between your flank and an armed terrorist.

Warren walked out 15 yards onto the still-snow-covered range and mounted his panel onto a stand a few feet high, then slid a thin sheet of aluminum behind it. "We're going to take this thing to failure," he said. I imagined it wouldn't be long before the aluminum was gnarled and fragmented beyond recognition.

It didn't happen. Over the next hour, Warren unloaded magazine after magazine from his AK-47. First, he fired directly from 15 yards, drilling the panel with 20 rounds, then another 20, all in practically the same spot. Then he emptied another clip a little to the left. Next, he fired off another 20 bullets while walking within 5 yards of the panel. He put down his AK-47, grabbed his M-14, and fired off another 10 rounds. Finally, he lofted the shotgun and discharged a last volley of punishment into the panel.

All told, the Magmacore withstood 135 rounds of bullets varying in shape, size, and velocity, all right on top of each other. (The steel currently protecting Humvees in Iraq will take about a dozen rounds in the same spot before giving way.) Though every shot had pierced the panel's exterior, not a single bullet had come out the other side. The only visible evidence that the panel took significant fire was a...