How a BB Gun Works

BB guns can use any of the operating mechanisms used for air guns; see the powerplant technology section of the air gun article. However, due to the limited accuracy and range inherent in the BB gun, only the simpler and less expensive mechanisms are generally used.

Since nearly all BBs used today are steel, it is common to find BB guns that use magnets in their loading mechanisms. Since the BB is too hard to be swaged to the bore size, magnets are often used to hold the BB at the rear of the barrel—otherwise, the BB would simply roll out of the barrel if it were held at a downward angle.

The traditional, and still most common powerplant for BB guns is the spring piston type, usually patterned after a lever action rifle or a pump action shotgun. The lever action rifle was the first type of BB gun, and still dominates the inexpensive youth BB gun market. The Daisy Model 25 BB gun, modeled after a pump action shotgun with a trombone pump action mechanism, dominated the low price, higher performance market for over 50 years. Lever action models generally have very low velocities, around 275 ft/s (84 m/s), a result of the weak springs used to keep cocking efforts low for use by youths. The Daisy Model 25 BB gun typically achieved the highest velocities of its day, ranging from 375 ft/s (114 m/s) to 450 ft/s (140 m/s). Lever action guns often have huge ammunition capacities; one of Daisy's early lever action models held 1000 BBs, in contrast to the Daisy Model 25 which held only 50 BBs. The ammunition in the lever action BB guns is gravity fed, such that the gun must be held at the proper angle when cocked to load the ammunition. The ammunition in the Daisy Model 25, on the other hand, is spring loaded, and no shift in gun angle is required to reload another BB.

Multi-pump pneumatic guns are also common—many youth oriented pneumatic pellet guns provide the ability to use BBs as a cheaper alternative to lead shot. These guns have rifled barrels, but the hard, slightly undersized BBs don't swage or obturate to fit the barrel, so the rifling may not impart a significant spin. These are the type of guns that will benefit most from using precision lead BB shot. The pneumatic BB gun attains much higher velocities than the traditional spring piston types. One interesting use of a pneumatic BB gun is in the calibration of ballistic gelatin, which is done by measuring the penetration of a steel BB at a velocity of about 600 ft/s (180 m/s).

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