Throat Erosion
Definition
Wear of the bore at the point where the rifling begins (the throat or leade), caused by hot propellant gas and bullet engraving. The most common cause of declining muzzle velocity in a heavily-fired barrel; advanced erosion reduces bullet guidance and increases gas bypass past the projectile.
- Location
- Bore area where rifling begins (the throat/leade)
- Cause
- Hot propellant gas plus bullet engraving friction
- Main symptom
- Declining muzzle velocity over the barrel's service life
- Advanced effect
- Poor bullet guidance and increased gas bypass
Common questions
How does throat erosion affect a firearms examiner's comparison work?+
As the throat wears, the rifling engraves the bullet less consistently, which can subtly change land and groove impressions over the barrel's life. An examiner comparing a fired bullet to a reference standard needs test-fires taken close in time to the evidence to account for this drift.
Which firearms suffer throat erosion fastest?+
High-pressure, high-velocity cartridges with hot-burning propellant, such as many magnum rifle rounds, erode the throat far faster than lower-pressure pistol calibres, so barrel life varies enormously by chambering rather than by round count alone.
Related terms
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- Piezoelectric Transducer
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