TV Guide National Geographic Channel Friday

Sean Rich, Larry 'Hammer' Harley and Jim Green travel to Colorado for an extravaganza of military collectibles, where Sean examines a 76lb bar of silver that may have come from the most famous Spanish shipwreck rescue in history. Hammer inspects what appears to be an authentic Keris sword with magical properties, while Jim goes to the shooting range with a Civil War re-enactor to see if his 1853 Enfield rifle fires

A student's dreams are challenged during advanced bombing training. High-speed dives lead to dangerous errors, prompting stern instructor feedback to maintain safety

A journey across Manitoba from South to North. The Winnipeg to Churchill train is filmed from above as it winds through snow-covered grasslands, Canada's Boreal Forest and into the frozen barren lands, just below the Arctic Circle. It's a constant struggle to keep on track as engineers battle with snow and ice in temperatures that reach as low as minus 45

Experts head beneath the waves to reveal the shocking secrets and doomsday weapons of the Cold War - the world's first nuclear-armed confrontation. The findings tell the story of the US atomic experiments and the warships they destroyed, including a submarine and a mighty aircraft carrier

Bidders vie for an 18th-century flintlock, a four-barrel gun so complex and expensive to produce that only the wealthy could afford one, making such items highly desirable. Sean Rich and his fellow Lords also inspect a piece of Second World War memorabilia possibly used by couriers behind enemy lines, which if authentic could be valued at $18,000