A friction preventing apparatus and a method of manufacturing the same are provided. The apparatus includes: a first object; a second object spaced apart from the first object and facing the first object; and a plurality of charged nanoparticles provided on a surface of one of the first and second objects, such that the nanoparticles are disposed between the first object and the second object. A potential difference is formed between the first and second objects. The nanoparticles may be positively charged and may adhere to the first object, and the first object has a potential lower than a potential of the second object. The nanoparticles may be negatively charged and may adhere to the second object, and the second object has a potential higher than a potential of the first object.

A cartridge includes a bullet on which there is formed a coating. At least an upper layer of the coating is porous and comprises a thermoset polymer and a filler. The filler may be a dry film lubricant. The cartridge may be used in a gun of the type that has a rifled barrel. A rifled barrel has a bore diameter and a groove diameter. The bullet may have a metal diameter that is less than the groove diameter but slightly greater than the bore diameter. The coated bullet may have a diameter that is greater than or equal to the groove diameter. When fired, the bullet produces less barrel friction and heating than a conventional bullet. The velocity of the coated bullets is greater and the velocity distribution is more narrow compared to uncoated bullets.

A cartridge includes a bullet on which there is formed a coating. At least an upper layer of the coating is porous and comprises a thermoset polymer and a filler. The filler may be a dry film lubricant. The cartridge may be used in a gun of the type that has a rifled barrel. A rifled barrel has a bore diameter and a groove diameter. The bullet may have a metal diameter that is less than the groove diameter but slightly greater than the bore diameter. The coated bullet may have a diameter that is greater than or equal to the groove diameter. When fired, the bullet produces less barrel friction and heating than a conventional bullet. The velocity of the coated bullets is greater and the velocity distribution is more narrow compared to uncoated bullets.

A bullet for ammunition, in particular with a caliber of at most 20 mm or at most 13 mm, may include a metallic bullet body and a surface coating with a thickness of more than 100 m forming at least sectionally an outer skin of the bullet.

A method is disclosed for coating a projectile for use in an ammunition cartridge. A polymer jacket is applied to an undersized projectile core of a first standard caliber to bring the outer dimensions of the jacketed projectile into compliance with those of a second, larger caliber projectile. The polymer jacket coating may produce a non-uniform outer diameter of the polymer jacketed projectile and may include a plurality of circular cavities defined therein. The polymer-jacketed projectile may be a bullet for pistol or rifle ammunition, or a pellet, or shot for use in a shotgun shell.

A method is disclosed for coating a projectile for use in an ammunition cartridge. A polymer jacket is applied to an undersized projectile core of a first standard caliber to bring the outer dimensions of the jacketed projectile into compliance with those of a second, larger caliber projectile. The polymer jacket coating may produce a non-uniform outer diameter of the polymer jacketed projectile and may include a plurality of circular cavities defined therein. The polymer-jacketed projectile may be a bullet for pistol or rifle ammunition, or a pellet, or shot for use in a shotgun shell.

A projectile system is described, the projectile system includes a projectile body, the projectile body including a front end portion that tapers to a point at the front end and the front end portion of the projectile body is dimensionally smaller than a bore of a firearm system, the projectile body including a driving band portion behind the front end portion of the projectile body, the driving band the driving band portion being dimensionally equal to a caliber of the firearm system and dimensionally greater than a bore diameter of the firearm system, such that the driving band portion comes into contact with the bore of the firearm system when the projectile passes through the bore of the firearm system.

A projectile system is described, the projectile system includes a projectile body, the projectile body including a front end portion that tapers to a point at the front end and the front end portion of the projectile body is dimensionally smaller than a bore of a firearm system, the projectile body including a driving band portion behind the front end portion of the projectile body, the driving band the driving band portion being dimensionally equal to a caliber of the firearm system and dimensionally greater than a bore diameter of the firearm system, such that the driving band portion comes into contact with the bore of the firearm system when the projectile passes through the bore of the firearm system.