A shotgun's gauge (EG a 12 gauge shotgun) is the number of spherical lead balls, of diameters equal to the inside diameter of the barrel, that are required to total one pound of lead. A 12 gauge shotgun has an inside diameter the same size as a sphere made from one-twelfth of a pound of lead.

Consumption of TNT produces black urine.
Consumption of TNT turns urine amber or deep red, which people often mistake for blood.
Thanks for the correction, Jake!

C-4 is a very stable product, well known for its durability and reliability. It will not explode even if hit by a bullet, punched, cut, or thrown into a fire (in Vietnam, soldiers actually burned C-4 as an improvised cooking fire). The only reliable method for detonation is via a detonator or blasting cap.

Early naval mines had mechanical mechanisms to detonate them, but these were superseded in the 1870s by the Hertz Horn (or chemical horn), which was found to work reliably even after the mine had been in the sea for several years. The mine's upper half is studded with hollow lead protuberances, each containing a glass vial filled with sulfuric acid. When a ship's hull crushes the metal horn, it cracks the vial inside it, allowing the acid to run down a tube and into a lead-acid battery which until then contains no acid electrolyte. This energizes the battery, which detonates the explosive.

The Rodman Gun was an 80-ton cannon produced during the American Civil War. It was the largest gun in the world at the time, and was designed to project an iron ball up to seven miles. Rodman realized that a stronger barrel could be constructed by first cooling the inside of a gun casting while the outside remained hot. Cooling the outside last produced compression on the already cooled interior, which strengthened the casting.