MIL-DTL-46540C(AR)
6.10 Changes from previous issues. Asterisks and marginal notes are not used in this revision to
identify changes with respect to the previous issue due to the extensiveness of the changes.
6.11 Critical defects.
6.11.1 Hangfire. A hangfire occurs when action time of a round is sufficiently long that the bolt
unlocks before the projectile leaves the muzzle of the barrel. This results in unrestrained combustion and
possible firing of the projectile out of battery. This could cause massive damage to the weapon system
and weapon stoppage (see 6.11.3). In addition, in an aircraft application, due to the weapon's proximity
to the user a hangfire will also present a safety hazard due to fragmentation and shrapnel from the weapon
and the round.
6.11.2 Projectile remaining in bore. A bullet in bore occurs when a projectile engages the rifling
of a barrel and travels some distance, but does not exit the barrel. This allows another cartridge to be
fired into the stuck projectile, causing catastrophic failure to the weapon system and weapon stoppage
(see 6.11.3). When used in an aircraft application, due to the barrel's proximity to the user a projectile
remaining in bore will also present a safety hazard due to fragmentation and shrapnel from the barrel and
the round.
6.11.3 Weapon stoppage. Due to the stand alone nature of the Land-based Phalanx Weapon
System, when an ammunition defect prevents the weapon from functioning, this is considered a Mission
Failure.
TABLE V. Critical defect justifications
Critical Defect
Justification
Split or perforated case
This will cause propellant loss and could prevent full opturation,
causing gas blow-by in the chamber. Either could result in a projectile
remaining in bore.
Failure to chamber
This will jam the feed mechanism of the weapon and cause weapon
stoppage.
Failure to extract
When the next round is chambered, it will jam the feed mechanism of
the weapon and cause weapon stoppage.
Split, K, L or M
When the next round is chambered, it will jam the feed mechanism of
the weapon and cause weapon stoppage.
Rupture, partial, L
When the next round is chambered, it will jam the feed mechanism of
the weapon and cause weapon stoppage.
Circumferential rupture,
When the next round is chambered, it will jam the feed mechanism of
complete
the weapon and cause weapon stoppage.
6.12 Subject term (key words) listing.
Cartridge Cases
20 millimeter
Custodian: Army-AR
Preparing activity: Army-AR
(Project 1305-2006-003)
NOTE: The activities listed above were interested in this document as of the date of this document.
Since organizations and responsibilities can change, you should verify the currency of the information
above using the ASSIST Online database at https://assist.daps.dla.mil
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