Fundamentals of Shooting Accuracy - ‘Challenges’
Accuracy and Precision
The accuracy of a shot depends on many factors. In addition to environmental conditions (external ballistics) and the skill of the shooter, it is primarily the interaction between the load and the barrel (internal ballistics) that influences the ballistic properties of the bullet as it leaves the muzzle.
The rifled barrel in new condition provides the basis for precision. Depending on the manufacturing process and material, the effort required to achieve quality and dimensional accuracy varies.
However, it is only in combination with the loading that it becomes clear whether the precision potential of a barrel can be exploited. The geometric position of the bullet when the shot is fired and the symmetry of the pressure development in relation to the barrel geometry determine the properties of the bullet as it leaves the muzzle.
Every shot leaves marks that change the geometry of the barrel over time. The barrel is subject to high stress during use: hot gases at high pressure drive the bullet through the barrel and, with the help of the spiral arrangement of the rifling and fields, cause it to rotate at the same time. The fields wear down (erosion), while residues from combustion and the bullet jacket form on the rifling and fields (deposits). During subsequent shots, the deposits are repeatedly pressed into the barrel surface.
Regular chemical/mechanical cleaning can reduce deposits to a minimum. If cleaning is not carried out, the deposits will corrode over time.
In addition, there are localised special events, such as material defects and expansions. The latter are caused, among other things, by obstacles in the barrel, which lead to pressure peaks during a projectile’s passage. These range from externally invisible expansions (including discolouration) on the inside to externally visible bulges and barrel explosions (so-called blowouts).
The condition of the barrel – contamination, erosion, deposits, corrosion and special events – affects the accuracy of the shot and can lead to a safety-critical failure of the weapon.
Both analogue optical and digital optical endoscopes are available today for non-destructive inspection of a barrel. However, they must be operated manually. Due to the twist, it is not possible to specifically inspect a rifling/field profile from the muzzle to the transition cone. This challenge gave rise to the idea for the IBoWV.
