Editing Terminal ballistics (section)

====Maximum penetration====
For use against [[Armoured warfare|armored targets]], or large, tough [[Game (hunting)|game animals]], penetration is the most important consideration. Focusing the largest amount of kinetic energy and projectile mass on the smallest possible area of the target provides the greatest penetration. Bullets for maximum penetration are designed to resist deformation on impact and usually are made of lead that is covered in a copper, brass, or mild steel jacket (some are even solid copper or bronze alloy). The jacket completely covers the front of the bullet, although often the rear is left with exposed lead (this is a manufacturing consideration: the jacket is formed first, and the lead is [[swage]]d in from the rear).

For penetrating substances significantly harder than jacketed lead, the lead core is supplemented with or replaced with a harder material, such as hardened steel. Military [[Armor-piercing shot and shell|armor-piercing]] small arms ammunition is made from a copper-jacketed steel core; the steel resists deformation better than the usual soft lead core leading to greater penetration. The current NATO [[5.56×45mm NATO|5.56mm]] SS109 (M855) bullet uses a steel-tipped lead core to improve penetration, the steel tip providing resistance to deformation for armor piercing, and the heavier lead core (25% heavier than the previous bullet, the M193) providing increased [[internal ballistics|sectional density]] for better penetration in soft targets. For larger, higher-velocity calibers, such as tank guns, hardness is of secondary importance to density, and are normally [[Sub-caliber round|sub-caliber projectiles]] made from [[tungsten carbide]], tungsten hard alloy, or [[depleted uranium]] fired in a light aluminum or magnesium alloy (or carbon fiber in some cases) [[Sabot (firearms)|sabot]].

Many modern tank guns are smoothbore, not rifled because practical rifling twists can only stabilize projectiles, such as an [[Armour-piercing, capped, ballistic capped shell|armor-piercing, capped, ballistic cap]], with a length-to-diameter ratio of up to about 5:1 and also because the rifling adds friction, reducing the velocity and thus total force it is possible to achieve. To get the maximum force on the smallest area, modern [[Anti-tank warfare|anti-tank]] rounds have aspect ratios of 10:1 or more. Since these cannot be stabilized by rifling, they are built instead like large darts, with fins providing the stabilizing force instead of rifling. These subcaliber rounds, called [[Kinetic energy penetrator|armor-piercing fin-stabilized discarding sabot]] are held in place in the bore by sabots. The sabot is a light material that transfers the pressure of the charge to the penetrator, then is discarded when the round leaves the barrel.