Squib Load
Definition
An underpowered cartridge where the propellant fails to generate enough gas to fully propel the bullet out of the barrel. The bullet lodges in the bore and can cause catastrophic damage if another round is fired before the obstruction is cleared.
- Cause
- Underpowered cartridge, insufficient propellant gas
- Outcome
- Bullet lodges in the bore
- Danger
- Catastrophic damage if another round is fired
- Related term
- Overlaps with squib in firearms examination
Common questions
Is squib load the same finding as squib in a firearms report?+
They describe the same underlying event, a round that fails to fully propel its bullet from the barrel, though squib load more often emphasises the cartridge as the cause and squib the resulting bore obstruction.
What evidence distinguishes a squib load from a bore obstruction caused by debris?+
Examiners look at the recovered case for signs of reduced propellant burn, such as unburned powder or a weak primer indent pattern, alongside the lodged bullet's position, to separate a cartridge-caused squib from an unrelated barrel blockage.
Related terms
- Chamber Pressure
- The gas pressure inside the firearm's chamber and bore during combustion of the propellant charge. Measured by piezoelectric transducer in psi (SAAMI)...
- Hangfire
- A delay between firing-pin strike and cartridge ignition, ranging from fractions of a second to several seconds. Caused by degraded or moisture-contaminated...
- Maximum Average Pressure (MAP)
- The SAAMI statistical ceiling for mean chamber pressure across a production lot of cartridges, at specified temperature and barrel conditions. CIP uses...
- Piezoelectric Transducer
- A quartz or ceramic crystal sensor mounted in a barrel port that converts chamber pressure to a measurable electrical charge. The basis...
- Slamfire
- Unintended cartridge ignition during bolt closure, without a discrete trigger pull. Caused by free-floating firing pin inertia or primer over-sensitivity. Produces automatic-like...
- Throat Erosion
- Wear of the bore at the point where the rifling begins (the throat or leade), caused by hot propellant gas and bullet...