While you won't see Seal Team Six storming walled compounds with iPhones strapped to their rifles, it doesn't mean yours isn't welcome at the range. Turn your device into an optical system with the Inteliscope Tactical Rifle Adapter ($70), a combination Picatinny or Weaver rail mount and iOS app that brings ballistics and environmental information to your next shoot. It has a HUD with custom crosshairs, digital zoom, video recording, compass, GPS, and all the data you could want. The reinforced mounting system protects your device, allows portrait and landscape orientation, and lets you aim around corners. It won't make you shoot like special ops, but it couldn't hurt.