<p>A .50-caliber BMG sniper rifle, in the wrong hands, would be terrorism unleashed.</p>
<p>The gun is powerful enough to punch a hole in an oil tank or take down a civilian airplane. Its 5 1/2-inch long bullets can pierce an inch of armor 40 yards away and hit a target a mile away. A massive weapon, with some models weighing in at 28 pounds, it's ill-suited for hunters -- it would take out a deer and the tree behind it -- but ideal for assassins.</p>