Topic 8 - Muzzle Attachments Flashcards
What is the flat end of the barrel called?
The crown
What can crown damage cause?
Markings
- Potentially deflect the bullet’s path.
- Anomalous markings and scratches on the bullet with potential forensic significance.
What is the noise we here when a firearm goes up caused by?
|Pressure wave, supersonic, mechanical
- Pressure wave from rapidly expanding gases going supersonic.
- Supersonic crack if the bullet goes supersonic.
- Mechanical action noise of the firearm itself
- Any other flight-related noises e.g. air friction
What is pressure wave caused by?
Ignition of propellant
The pressure wave is caused by the rapidly expanding gases produced from ignition of the propellant inside the ammunition cartridge case becoming supersonic as they leave the muzzle.
What sound component can be reduced with a sound suppressor?
The supersonic pressure wave is generally the only sound component from the firearm that can be reduced by using a sound suppressor.
What do sound suppressors do?
They reduced the sound produced by supersonic gases
Why are sound suppressors ineffective?
- There are other sources of sound
- Supersonic bullets create their own “sonic boom”
When can suppressors be useful? (ammunition)
Subsonic ammunition
What are the legal restrictions on sound suppressors?
Legally, they are prohibited unless specified on a firearms certificate for a particular weapon.
How do sound suppressors work?
Slowing, expansion, turbulence, controlled chamber
- Sound suppressors function by slowing the gases leaving the muzzle.
- This is achieved by allowing expansion of the gases and applying turbulence to the gas flow within a controlled chamber (the suppressor) to slow down the gases to below the speed of sound upon release to the external environment.
What are basic components of a sound suppressor?
- Expansion chamber
- Baffles
What are the different types of sound suppressors?
- Can
- Baffle
- Reflex
- Active
What is a can suppressor?
A hollow can-shaped extension on the muzzle: not very effective.
What is a baffle?
A can with partitions for the pressure wave to impact and transfer energy to (losing velocity).
What is a reflex?
Internal complexity
A can with baffles and additional internal complexity, providing expansion chambers behind the baffles for the pressure wave to impact and transfer more energy to.
What is an active sound suppressor?
spring-loaded
A reflex suppressor with spring-loaded baffles which further transfers the energy away from the pressure wave.
Where should a sound suppressor be mounted?
Concentric to the bore axis
What happens if the sound suppressor is mounted wrong?
The suppressor can shatter
How are suppressors checked to ensure they’re safe?
Suppressors must be proof tested and may be certified safe for the ammunition that they are designed to be used with.
What are the different types of recoil reducers?
Compensators
- “Muzzle brakes” - external accessories & the most effective.
- “Recoil compensators” - integral to the firearm & less effective.
How do recoil reducers work?
Redirecting, muzzle brake, rearwards
- They work by redirecting propellant gases to counter the recoil of the firearm.
- Combustion gases will typically leave the muzzle brake at an angle pointing in a rearwards direction, acting like a thruster on an aircraft to pull the weapon in the opposite direction to the recoil forces.
When is recoil the highest and lowest?
Recoil is usually greatest for large-caliber slow moving projectiles and is less for fast small-caliber projectiles
What do typical forms of recoil reducers include?
Tube
- A short length of tube attached at 90o to the end of the barrel, diverting the gases sideways to counteract the gases normally pushing the barrel
upwards. - Laser-cut slots in the muzzle end of the barrel (Magna porting).
What are the drawbacks of recoil reducers?
Gas blast
- Recoil reducers will increase the noise of the firearm and the gas blast is directed back towards the firer.
- They could also give away covert positions by disturbing debris on the ground.
What causes muzzle flash?
Incandescent gases
The very hot mixture of incandescent gases and partially burnt propellant ignites in contact with the oxygen in the air causing an intense “muzzle flash”.
What do flash hiders do?
Longitudinal cuts
- Physically hide the flash through the use of a a cone-shaped device on the end of the end of the barrel; or
- By dispersing the flash upwards or sideways via a series of fingers or a tube with longitudinal cuts. This is often part of a dual-purpose suppressor with a recoil reducer.
What are grenade dischargers?
Over the barrel
- Grenade dischargers are essentially a cup attached to the end of a rifle barrel into which a grenade can be launched via a blank cartridge.
- Or, the grenade can fit straight over the barrel and be fired with bulleted rounds which are caught with an aluminium or steel baffle.
What are recoil boosters?
Automatic
They are used to increase the rate of fire of short-recoiling automatic weapons. (Rg Mg-34 machine gun)
What is a shotgun choke?
Constriction
A choke is a constriction at the end of a shotgun’s barrel and is used to tailor the shot pattern for different purposes.
How are chokes formed?
Threading
Chokes may either be formed as part of the barrel at the time of manufacture, by squeezing the end of the bore down over a mandrel,or by threading the barrel and screwing in an interchangeable choke tube.
What do shotgun chokes typically consist of?
Conical section
The choke typically consists of a conical section that smoothly tapers from the bore diameter down to the choke diameter, followed by a cylindrical section of the choke diameter.
What have interchangeable chokes made easy?
Desired performance
The use of interchangeable chokes has made it easy to tune the performance of a given combination of shotgun and shot shell to achieve the desired performance.
What does a choke do to the diameter of the shot column?
Outer layers, inward acceleration,
- As the column of shot in the barrel reached the choke in the barrel, the diameter of the shot column is reduced, thus elongating its length.
- This results in the outer layers of the shot in the column being given inward acceleration, delaying the spreading of the shot after leaving the barrel and reducing its dispersion.
What are typical varieties of shotgun chokes?
- Full (0.004”)
- Three-quarters (0.003”)
- Half (0.002”)
- Quarter (0.001”)
- Improved cylinder (0.0005”)
- Cylinder (no restriction)
- All calibers should give the same spread of shot with a given choke
