Firearm is a term used to refer to small arms, portable guns that can be carried by a single person. The smallest of all firearms is the handgun. There are three common types of handguns: single-shot pistols, revolvers, and semi-automatic pistols. Firearms are also categorized by their functioning cycle or "action" which describes its loading, firing, and unloading cycle. These include manual (Single-shot and repeating), Semi automatic (self-reloading), and Automatic (Gatling, Maxim, Lewis, MG 08 guns), Machine guns (belt-fed ammunition), etc. 

Firearm Calculators

• Sectional Density: Computes the factor used in the computation of the ballistic coefficient called sectional density.
• Bullet Ballistic Coefficient: Computes factor that represents a bullet's ability to overcome air resistance in flight.
• Ballistic Coefficient from Bullet's Mass, Diameter and Form Factor: Estimates the ballistic coefficient from the mass, diameter and form factor
• Miller Twist Rule: Computes the optimal barrel twist rate for stabilizing a bullet's flight given the bullet's diameter, length and mass.
• Taylor Knock-out Factor: Calculates a factor indicating the power of a round,.
• Greenhill Formula for Optimal Rifling Twist Rate: calculate the optimal barrel twist rate for stabilizing a bullet's flight given the bullet's diameter, length, specific gravity and velocity. 
• Bullet Flight Range: Computes the maximum range (horizontal distance) traveled by a bullet based on the muzzle velocity, elevation angle and shooter height.
• Muzzle Energy of a Projectile: Calculates the kinetic energy in a bullet immediately after leaving the barrel given the bullet's mass and velocity.
• Recoil Velocity of a Gun: Computes the velocity at which a gun will move in the opposite direction in relation to the projectile that it fired.
• Cost per Round: Computes cost per round of ammunition based on the cost of a container of cartridges and the number of rounds in the container.
• Rifle Sight Correction Angles: Computes the Minutes of Angle corrections for rifle sights.
• Shotgun Shell Reloading Cost: Computes the cost to reload used shotgun shells (hulls) with powder, shot, wads and primers.
• Shotgun Shell Loading Cost: Computes the cost to load new pre-primed shells (hulls) with power, shot and wads. 
• Metal Ball Weight: Computes the mass (weight) of a spherical metal (e.g., steel) ball based on the size (diameter).
• Metal Cylinder Weight: Computes the mass (weight) of a metal cylinder based on the size (diameter and length).