Airgun
Steel BBs 4.5mm (1500)

BB guns are a type of air gun designed to fire spherical projectiles similar to shot pellets of approximately the same size.
Modern BB guns usually have a barrel with a bore and caliber of 4.5 mm (0.177 in) and are available in many varieties.
BB shot for modern BB guns is usually steel, plated either with zinc or copper to resist corrosion, and measure 4.3 to 4.4 mm (0.171 to 0.173 in) in diameter.
Some manufacturers still make lead balls of slightly larger diameter which are generally intended for use in rifled BB gun barrels.