Half-jacket - A short bullet jacket, or a bullet swaged with a short jacket, which leaves some lead in contact with the bore. A three-quarter jacket is similar but longer, so the bearing surface of the bullet is covered by the jacket material.


Handloading - The practice of loading or reloading small arms ammunition by hand-powered equipment and methods.


Hangfire - Slang term for a delayed firing, which is any detectable delay in the ignition of a cartridge after pulling the trigger. Can be a chemical delay caused by the cartridge or a mechanical delay caused by a defect in the firearm. Chemical delays are recognized as being less that 0.3 second. The use of modern lead styphnate priming has virtually eliminated the chemical delay. Chemical delays were more common with the now-obsolete potassium chlorate priming compounds.


Headspace - The distance from that surface of the barrel or chamber that prevents the cartridge from moving further forward into the chamber, to the face of the breech with the action fully closed and locked. This is the most important dimension governing the safety of the shooter.


Heel - The edge of the bullet base.


Holdover - The vertical distance a shooter must aim above a target to obtain a hit at ranges greater than the gun's "zero." See zero.


Hollow Point (HP) - Bullet design feature; an axial hole in the tip of a bullet to speed the release of energy into a target and reduce the chance of over-penetration.


Hot-Cor - The trademark for Speer's exclusive process of manufacturing flat-base rifle bullets. A molten core is poured into a clinically clean jacket and then the bullet is immediately swaged to shape, with a resulting tight bond between core and jacket.


Hydrostatic Shock - A pressure wave created by a bullet passing through animal tissue, which is high in water content.