Taylor Knock Out Factor

The Taylor Knock-out Factor calculator approximates the stopping power of a cartridge based on its bullet mass, velocity, and diameter.

INSTRUCTIONS: Choose units and enter the following:

• (M) Mass of Bullet
• (V) Velocity of Bullet
• (D) Diameter of Bullet

Taylor Knock-out Factor (TKOF): The returns the Taylor Knock-out Factor as a real number.  It also returns the kinetic energy (KE) of the bullet in Foot-pounds.  However, this can be automatically converted to compatible units (e.g., Joules) via the pull-down menu.

The Math / Science

The formula for the Taylor Knock-out Factor is:

`TKOF = (M*V*D)/7000`

where:

• TKOF = Taylor Knock-out Factor
• M = Mass of the bullet converted to grains.
• V = Velocity of the bullet converted to feet per second.
• D = Diameter of the bullet converted to inches.

The Taylor Knock-out factor was developed by big game hunter John Taylor in the mid 20th century as a way for him to compare the power not only of different cartridges but the same cartridge between different rifles, where velocity can vary with barrel length and other factors. It is calculated by multiplying the mass, velocity, and diameter together and dividing by 7000, the number of grains in a pound. The result is a unitless value known as the Taylor Knock-out Factor which normally varies from 0-150 with typical cartridges. Anything above 30 is a very powerful cartridge, some examples based on typical loads include the .375 H&H Magnum with a TKOF of ~35, the .416 Rigby with a TKOF of ~57, and the .600 Nitro Express with a TKOF of ~147. Most common pistol cartridges come in from about 1-15 with .22 long rifle being about TKOF of ~1.3, 9mm at around TKOF ~7 and .45 ACP at TKOF ~12.

The formula for Kinetic Energy is:

KE= ½⋅m⋅v²

where:

• KE is the kinetic energy
• m is the mass of the bullet
• v is the bullet's velocity 

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).

References

https://en.wikipedia.org/wiki/Taylor_knock-out_factor