The meplat (from the
French word "''méplat''" meaning "flat surface of a cylinder") is the technical term for the flat or open tip on the nose of a
bullet
A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constru ...
. The shape of the meplat is important in determining how the bullet moves through the air. In particular the size and shape of the meplat has a significant effect on the
ballistic coefficient of a bullet.
Theory
''Trimming'' the meplat (cutting the tip of the bullet, thus increasing its area) decreases the bullet's ballistic coefficient, increasing drag, and making it more susceptible to wind drift. So even though the grouping will be tighter, the time of flight and wind drift will be slightly greater.
''Pointing'' the meplat (reducing its area) involves pressing the bullets into a special die. This decreases the size of the meplat which increases the ballistic coefficient, which reduces drag, time of flight, and wind drift of the bullet.
Some target shooters sort their bullets by weight, point their bullets, and then trim them to the same meplat width to ensure the greatest possible consistency.
Meplats are often used to increase the bullet's
wounding ability.
The shape of the nose of an axisymmetric projectile that gives it the least possible
aerodynamic drag
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or b ...
at
hypersonic speeds always has a meplat, the diameter of which depends on the length of the nose.
[A.J. Eggers, Jr., Meyer M. Resnikoff, and David H. Dennis, "Bodies of Revolution Having Minimum Drag at High Supersonic Speeds", NACA Report 1306, 1955.]
Varying meplats
If the meplats on a group of bullets are uneven, the trajectory of the bullets will vary which will cause the bullets to strike the target at different vertical locations.
Bullets of the same mass that have similar-shaped meplats will travel through the air in nearly identical fashion, making it easier to
group shots together or hit a
target multiple times. For this reason,
competitive shooters and
snipers often trim or point their meplats to uniform shape.
Rounds of the same
caliber
In guns, particularly firearms, but not #As a measurement of length, artillery, where a different definition may apply, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge ( ...
, but with different-shaped meplats sometimes cannot be loaded into the same firearm. The meplat plays an important role in the loading of weapons whose ammunition is guided into the chamber by a mechanism (e.g.,
semi-automatic,
pump-action
Pump action is a type of manual firearm action that is operated by moving a sliding handguard on the gun's forestock. When shooting, the sliding forend is pulled rearward to eject any expended cartridge (firearms), cartridge and typically to co ...
,
lever-action, or
bolt-action
Bolt action is a type of manual Action (firearms), firearm action that is operated by ''directly'' manipulating the bolt (firearms), turn-bolt via a cocking handle, bolt handle, most commonly placed on the right-hand side of the firearm (a ...
firearms), though this usually is not as important in weapons whose rounds are chambered individually by hand (e.g.,
single-shot
In firearm designs, the term single-shot refers to guns that can hold only a single round of ammunition inside and thus must be reloaded manually after every shot. Compared to multi-shot repeating firearms ("repeaters"), single-shot designs have ...
s,
multiple-barrel firearms,
combination guns, or
revolver
A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, ...
s.)
See also
*
Full metal jacket bullet
*
Hollow-point bullet
*
Semiwadcutter
*
Soft-point bullet
*
Wadcutter
References
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Ammunition