Patent attributes
An improved sub-sonic cartridge for small arms containing a bullet whose Calibers (length/diameter) value is 6.0 or greater, which imparts to the bullet substantially greater kinetic energy than smaller and lighter sub-sonic bullets. The greater kinetic energy of the bullet aids in cycling the action of semi and fully automatic firearms as well as imparts greater kinetic energy to the target upon impact. The bullet incorporates an fin unit on the aft portion of the bullet; the aft fin unit is rotationally independent of the rotational state of the bullet in flight. The fin unit forces the Center of Pressure rearward of the Center of Gravity for added stability and accuracy in flight. Volume vacant of propellant within the cartridge shell may be occupied with a durable and heat resistant material to aid in consistent and reliable propellant burn when fired.