Although a shorter barrel generally results in lower muzzle velocity, Polygonal rifling partially compensates from the loss of velocity from a shorter barrel.

Polygonal rifling may leave striations that are difficult to match to a particular barrel.

The Polygonal Map Quadtree ( or PMQuadtree ) is a variation of quadtrees which are used to store collections of polygons that may be degenerate ( meaning that they have isolated vertices or edges ).

Runner is released by Atari Games and is known for early use of high-speed 3-D Polygonal Graphics.

Polygonal modeling is well suited to scanline rendering and is therefore the method of choice for real-time computer graphics.

Fort Nelson is a typical Polygonal or Palmerston Fort.

Polygonal forms apparently caused by frost heave have been observed in near-polar regions of Mars by the Mars Orbiter Camera ( MOC ) aboard the Mars Global Surveyor and the HiRISE camera on the Mars Reconnaissance Orbiter.

Polygonal approximations are linearly dependent on the curve in a few select cases.

Polygonal battle axe, from Dalarna

Polygonal barrels tend to have longer service lives because the reduction of the sharp edges of the land ( The grooves are the spaces that are cut out, and the resulting ridges are called lands ) reduces erosion of the barrel.

* Polygonal walls.

( Compare these diagrams with the diagrams in Polygonal number.

It was to be called, meaning literally Polygonal Block.

* Polygonal Modeling in Alias 9. 0 ( 120 pages )-Tools to create and modify polygons and polysets.

Spin is induced by gun barrels having rifling which engages a soft metal band around the projectile, called a " driving band " ( UK ) or " rotating band " ( U. S .).

The primary benefits over rifled barrels is reduced barrel wear, longer ranges that can be achieved ( due to the reduced loss of energy to friction and gas escaping around the projectile via the rifling ) and larger explosive cores for a given caliber artillery due to less metal needing to be used to form the case of the projectile because of less force applied to the shell from the non-rifled sides of the barrel of smooth bore guns.

A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves (" rifling ") cut into the barrel walls.

Although uncommon, polygonal rifling is still used in some weapons today with one example being the Glock line of pistols ( which fire standard bullets ).

This is rare on rifles designed for extreme accuracy, as the plating process is difficult and liable to reduce the effect of the rifling.

Up to a certain limit this is effective, but once the projectile's length is more than six or seven times its diameter, rifling becomes less effective.

Slugs are stabilized in flight by rifling in the barrel, which causes the slug to spin, or are stabilized as a dart is by the weight center of balance being forward of the aerodynamic center of balance, sometimes with assistance from fins.

The term of art is not meant to connote anything about whether the weapon's barrel had received the further machining step of rifling the barrel, so there are two broad classifications: rifled muzzleloaders and smooth bore muzzleloaders.

In rifles firing round ball, a lubricated patch of fabric is wrapped around the base of the ball which grips the rifling and imparts spin to the ball.

In Minié rifles, no patch is used as the projectile has a base which expands to grip the rifling.

In the case of rifled weapons, the contour of a muzzle is designed to keep the rifling safe from damage, so it is commonly recessed or protected by a convex " crown ".

In some cases, rifling will have twist rates that increase down the length of the barrel, called a gain twist or progressive twist ; a twist rate that decreases from breech to muzzle is undesirable, as it cannot reliably stabilize the bullet as it travels down the bore.

The spiraling pattern ( here with normal rifling ) is shown.

For tanks and artillery pieces, the extended range, full bore concept developed by Gerald Bull for the GC-45 howitzer reverses the normal rifling idea by using a shell with small fins that ride in the grooves, as opposed to using a slightly oversized projectile which is forced into the grooves.

After engaging the rifling the bullet is progressively subjected to accelerated angular momentum as burning powder propels it down the barrel.

By only gradually increasing the spin rate, torque is spread along a much longer section of barrel, rather than only at the throat where rifling is eroded through repeated rifling engagement.

Most rifling is created by either:

* pressing all grooves at once with a tool called a " button " that is pushed or pulled down the barrel ( button rifling );

In 1826 Delvigne, a French infantry officer, invented a breech with abrupt shoulders on which a spherical bullet was rammed down until it caught the rifling grooves.

Bullets leaving a rifled barrel can spin at over 100, 000 revolutions per minute ( rpm ) depending on the muzzle velocity of the bullet and the pitch of the rifling.

The original muzzle-loading rifle, on the other hand, with a more closely fitting ball to take the rifling grooves, was more difficult to load, particularly when the bore of the barrel was fouled from previous firings.

In 1826, Delvigne, a French infantry officer, invented a breech with abrupt shoulders on which a spherical bullet was rammed down until it caught the rifling grooves.

About 1862 and later, W. E. Metford carried out an exhaustive series of experiments on bullets and rifling, and invented the important system of light rifling with increasing spiral, and a hardened bullet.

When the projectile is swaged into the rifling, it takes on a mirror image of the rifling, as the lands push into the projectile in a process called engraving.

Russian 122 mm shrapnel shell ( which has been fired ) showing rifling marks on the copper alloy driving band around its base

* Article on making and measuring rifling by Lilja ; includes pictures of button rifling machine

The Lee-Enfield bolt action system was introduced in 1889 with the Lee-Metford and later Lee-Enfield rifles ( the bolt system is named after the designer and the barrel rifling after the Royal Small Arms Factory at Enfield ), and is a " cock on closing " action in which the forward thrust of the bolt cocks the action.

The spiral grooves of rifling make rifles more accurate and give a longer effective ranges – but on a muzzle-loading firearm they take more time to load due to the tight-fitting ball, and after repeated shots black powder tended to foul the barrels.

The FAMAS G2 was developed c. 1994 to bring the rifle more in compliance with NATO standards by having tighter rifling and accepting standard NATO magazines, but also included several other upgrades taken from the G1 model, such as the enlarged trigger guard and improved hand guards made of fiber glass, rather than plastics like on the F1.

Booth's Deringer was unusual in that the rifling twisted counterclockwise ( left-handed twist ), rather than the typical clockwise twist used on most Philadelphia Deringers.

Russian 122 mm shrapnel shell ( which has been fired ) showing rifling marks on the copper alloy driving band around its base

The advantage in using plastic as a swage material in such cases is reduced wear on the barrel rifling, extending the life and average accuracy of the weapon.

Gerald Bull worked extensively on ways to eliminate the driving band, leading to the development of his Extended Range, Full Bore ammunition using an inversion of the pre-cut rifling for his GC-45 howitzer, which is now rapidly replacing older artillery worldwide.

Yet with the removal of the rifling and the soft-metal driving band on the shell itself, the shell could be designed purely for ballistics, as opposed to having the external constraint of the driving band.

Through the combination of a leather wad and tight grooves on the inside of the barrel ( rifling ), this weapon was far more accurate, though slower to load.

The original. 50 Action Express bore diameter was. 500 " with conventional rifling, but the switch to polygonal rifling on production Desert Eagles Pistols allowed the gauge plug to drop through, rendering the gun a destructive device under Bureau of Alcohol, Tobacco, Firearms and Explosives ( BATFE ) regulations.

When fired, the expanding gas pushed forcibly on the base of the bullet, deforming it to engage the rifling.