Transition Ballistics
   HOME

TheInfoList



OR:

Transitional ballistics, also known as intermediate ballistics,Ballistics
at Encyclopædia Britannica Online, Accessed April 27, 2009
is the study of a
projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found in ...
's behavior from the time it leaves the muzzle until the pressure behind the projectile is equalized, so it lies between
internal ballistics Internal ballistics (also interior ballistics), a subfield of ballistics, is the study of the propulsion of a projectile. In guns, internal ballistics covers the time from the propellant's ignition until the projectile exits the gun barrel. The s ...
and
external ballistics External ballistics or exterior ballistics is the part of ballistics that deals with the behavior of a projectile in flight. The projectile may be powered or un-powered, guided or unguided, spin or fin stabilized, flying through an atmosphere or ...
.


The transitional period

Transitional ballistics is a complex field that involves a number of variables that are not fully understood; therefore, it is not an
exact science The exact sciences, sometimes called the exact mathematical sciences, are those sciences "which admit of absolute precision in their results"; especially the mathematical sciences. Examples of the exact sciences are mathematics, optics, astron ...
. When the bullet reaches the muzzle of the barrel, the escaping gases are still, in many cases, at hundreds of atmospheres of pressure. Once the bullet exits the barrel, breaking the seal, the gases are free to move past the bullet and expand in all directions. This expansion is what gives gunfire its explosive sound (in conjunction with the
sonic boom A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to t ...
of the projectile), and is often accompanied by a bright flash as the gases combine with the
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
in the air and finish combusting. The propellant gases continue to exert force on the bullet and firearm for a short while after the bullet leaves the barrel. One of the essential elements of
accurizing Accurizing is the process of improving the accuracy and precision of a gun (firearm or airgun). For firearms, accuracy is the ability to hit exactly what one is aiming at, and precision is the ability to hit the same place over and over again in ...
a firearm is to make sure that this force does not disrupt the bullet from its path. The worst case is a muzzle or muzzle device such as a flash-hider that is cut at a non-square angle, so that one side of the bullet leaves the barrel early; this will cause the gas to escape in an asymmetric pattern, and will push the bullet away from that side, causing shots to form a "string", where the shots cluster along a line rather than forming a normal
Gaussian Carl Friedrich Gauss (1777–1855) is the eponym of all of the topics listed below. There are over 100 topics all named after this German mathematician and scientist, all in the fields of mathematics, physics, and astronomy. The English eponymo ...
pattern. Most firearms have muzzle velocities in excess of the ambient
speed of sound The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as w ...
, and even in subsonic cartridges the escaping gases will exceed the speed of sound, forming a
shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a med ...
. This wave will quickly slow as the expanding gas cools, dropping the speed of sound within the expanding gas, but at close range this shockwave can be very damaging. The muzzle blast from a high powered cartridge can literally shred soft objects in its vicinity, as careless benchrest pistol shooters occasionally find out when the muzzle slips back onto their sandbag and the muzzle blast sends sand flying.


Initial velocity calculation

During the first part of the intermediate ballistics period the real velocity of the projectile increases. It is caused by the propellant gases exiting the muzzle. For that reason the real maximum projectile velocity (Vmax) is higher than the real muzzle velocity (Vr). The external ballistics uses so-called initial velocity Vo, which is not the same as the real muzzle velocity. The initial velocity Vo is calculated via an extrapolation of the decaying part of velocity curve to the position of the muzzle (to). The difference between these two velocities is visible in the chart.


Altering transitional ballistics

In addition to the process of "crowning" a barrel to ensure a clean and accurate exit of the bullet, there are a number of devices that attempt to harness the muzzle blast for various reasons.


Suppressing the blast

Flash suppressor A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a muzzle device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that ...
s and
sound suppressors A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a Gun barrel#Muzzle, muzzle device that reduces the Sound intensity, acoustic intensity of the muzzle report (sound of a gunshot) and muzzle rise when a gun (fir ...
are the most obvious devices that operate in the transitional ballistics realm. These both alter the flow of the escaping gas to reduce the effects of the muzzle blast. Flash suppressors introduce turbulence into the mixing of fuel-laden hot gases escaping from the muzzle and the surrounding oxygen-rich air, reducing combustion efficiency and thus reducing the size and brightness of the flash. Sound suppressors slow the expansion of gases, allowing it to cool and reducing the rate at which it escapes to prevent a shockwave from forming. A ''
recoil compensator A muzzle brake or recoil compensator is a device connected to, or a feature integral to the construction of, the muzzle or barrel of a firearm or cannon that is intended to redirect a portion of propellant gases to counter recoil and unwanted ...
'' is designed to direct the gases upwards at roughly a right angle to the bore, in essence making it a small
rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely fr ...
that pushes the muzzle downwards, and counters the "flip", or
rise Rise or RISE may refer to: Arts, entertainment, and media Fictional entities * '' Rise: The Vieneo Province'', an internet-based virtual world * Rise FM, a fictional radio station in the video game ''Grand Theft Auto 3'' * Rise Kujikawa, a vide ...
of the muzzle caused by the high bore line of most firearms. These are often found on "raceguns" used for
action shooting Practical shooting, also known as dynamic shooting or action shooting, is a set of shooting sports where the competitors try to unite the three principles of precision, power, and speed, by using a firearm of a certain minimum power factor to score ...
and in heavy, rifle caliber handguns used in
metallic silhouette Metallic silhouette shooting is a group of target shooting disciplines that involves shooting at steel targets representing game animals at varying distances, seeking to knock the metal target over. Metallic silhouette is shot with large bore rifl ...
shooting. In the former case, the compensator serves to keep the sights down on target for a quick follow-up shot, while in the latter case they keep the heavy recoil directed backwards, preventing the pistol from trying to twist out of the shooter's grip. A ''
muzzle brake A muzzle brake or recoil compensator is a device connected to, or a feature integral to the construction of, the muzzle or barrel of a firearm or cannon that is intended to redirect a portion of propellant gases to counter recoil and unwanted ...
'' is designed to redirect the muzzle blast backwards, and therefore counter the recoil of the bullet. Muzzle brakes tend to be found on larger firearms, such as magnum rifles and
artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...
. A well designed muzzle brake can significantly reduce recoil, turning a rifle that would otherwise be punishing to shoot into a far more tolerable experience. A good example may be seen on the M82 Barrett sniper rifle. There are downsides to both recoil compensators and muzzle brakes. They direct more of the muzzle flash to the sides or back towards the shooter—this is especially true of muzzle brakes. While eye and ear protection should always be used when shooting, this is even more essential with the muzzle blast directed back towards the shooter. Brakes and compensators are often quite bulky, adding length, diameter, and mass to the muzzle end of the firearm where it will affect the firearm's handling worst. While a simple slot milled in the barrel, such as those used in Magna-Porting, will provide some benefit, efficient redirection of the gas flow requires large ports and baffles to deflect as much gas as possible. It is also highly inadvisable to fire
sabot Sabot may refer to: * Sabot (firearms), disposable supportive device used in gunpowder ammunitions to fit/patch around a sub-caliber projectile * Sabot (shoe), a type of wooden shoe People * Dick Sabot (1944–2005), American economist and busi ...
rounds like shotgun slugs or APDS rounds through a muzzle brake not designed for them.


References

{{DEFAULTSORT:Transitional Ballistics Ballistics Articles containing video clips