|Rifling And Twist Rates:|
|Rifled Barrel Terms:|
Barrel - The part of the rifle through which projectiles pass in their travel from the chamber or breech to the muzzle.
Bore - The interior of a rifle's barrel excluding the chamber.
Rifling - Spiral grooves in a gun's bore that consist of lands (The highest part of the rifling) and grooves (The lowest part of the rifling) which spin the projectile in flight and impart accuracy.
Rifling is present in all true rifles. Rifled bores may be described by the bore diameter which is the diameter across the lands in the rifling, or by groove diameter which is the diameter across the grooves in the rifling.
Rifling Twist Rates:
What does the rifling twist rate do:
How do you know what rifling twist is right:
If an insufficient twist rate is used, the bullet will begin to yaw and then tumble; this is usually seen as "keyholing", where bullets leave elongated holes in the target as they strike at an angle.
Once the bullet starts to yaw, any hope of accuracy is lost, as the bullet will begin to veer off in random directions.
A too-high rate of twist can also cause problems. The excessive twist can cause accelerated barrel wear, and in high velocity bullets an excessive twist can cause bullets to literally tear themselves apart under the centrifugal force.
The centrifugal force of a bullet helps to expand the bullet when the bullet impacts a solid object. Velocity and rifling twist rate determine the ballistic centrifugal force of a bullet so barrel length and barrel twist rate together changes the bullets centrifugal force and as a bullet travels downrange the R.P.S. value is constantly decreasing.
Choosing the right rifle:
Measuring the rifling twist rate in a rifle barrel:
|Resources And References:|