Video—First Look: Smith & Wesson M&P9 M2.0 Subcompact Pistol

Firearms and ammunition ballistics have changed greatly over the last half-century, but one of the biggest leaps in performance hit the scene five decades ago, when Burris Optics introduced its Fullfield line of riflesopes.

In the mid-1970s, the German federal police sought a replacement for its existing World War II-era sidearms and put out stringent guidelines for what it wanted in a handgun. The result was the Heckler & Koch P7.

Smith & Wesson's new Shield X micro-compact handgun combines elements from the company's M&P Shield Plus with some cues from its smaller Bodyguard 2.0 design.

The idea that a faster-moving, lightweight projectile can do the same work as a heavier, slower-moving slug has been around for ages, and the math clearly supports it, even if some in the general public don’t.

The Y.E.S. program—which launched in 1996—is held each summer in Washington, D.C., and brings together high-achieving high school students from across the country for a week of immersive learning focused on the U.S. Constitution, Bill of Rights and American government.