Blank Cartridge Recessed Primer and Matching Bolt Interlock
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Solution Overview
Problem
Existing blank ammunition cartridges lack a mechanism to prevent inadvertent firing when used with live-fire rifles or traditional bolts, posing safety risks during training exercises.
Innovation Solution
A blank cartridge with a recessed primer and a corresponding bolt featuring a breech face protrusion that ensures proper chambering and locking only when used together, preventing firing with mismatched ammunition types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional flush primer design is used in blank ammunition cartridges, then the cartridge can be fired with any standard bolt, but the safety mechanism to prevent inadvertent firing with live-fire rifles is lost
Solution Approach 1:
The patent applies asymmetry by creating a non-standard recessed primer pocket configuration that is asymmetric relative to traditional flush primer designs. The recessed primer pocket extends into the cartridge base by a specific distance (0.005-0.020 inches), creating a unique geometric profile that only matches the corresponding protrusion on modified bolts. This asymmetric design ensures that blank cartridges with recessed primers can only be properly chambered and fired with bolts that have the matching recess accommodation feature, thereby preventing inadvertent firing with standard live-fire rifles while maintaining compatibility with the specific modified bolt design.
2Reliability
If the primer is recessed into the cartridge base, then safety is improved by preventing firing with mismatched ammunition, but the bolt design complexity increases due to the required protrusion feature
Solution Approach 1:
The patent applies preliminary action by pre-configuring the bolt with a protrusion feature on the breech face that corresponds to the recessed primer pocket depth. This protrusion is built into the bolt design from the outset, so that when the cartridge is chambered, the protrusion automatically aligns with and contacts the recessed primer. This preliminary configuration ensures proper alignment and prevents inadvertent firing before the shooting action begins, rather than requiring additional safety mechanisms or adjustments during operation.
3Reliability
If a recessed primer pocket is created in the cartridge casing, then proper engagement with the bolt protrusion is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by specifying a controlled range for the recess depth (0.005-0.020 inches) rather than requiring a single precise dimension. This parameter range accommodates normal manufacturing tolerances while ensuring reliable engagement with the bolt protrusion. The recess depth is designed to work within this range, allowing manufacturers to produce cartridges with acceptable precision levels without compromising the safety function. The corresponding bolt protrusion is designed to complement this range, ensuring proper contact and alignment across the tolerance band.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances safety by ensuring that blank cartridges can only be fired with the correct bolt, thereby preventing accidental ignition of live rounds.
Implementation Method 1
A protrusion on the breech face extends axially from the breech face by an amount corresponding to the recess distance of the primer
Data Source
AI summary
An ammunition cartridge casing has a casing base with a proximal end surface, a casing body defining an inside volume, and a distal end portion. The casing base defines a primer pocket in communication with the inside volume of the casing body, where the primer pocket is sized and configured such that when a primer is installed in the primer pocket, a proximal face of the primer is recessed into the base at least 0.010″ with respect to the end surface. Blank ammunition made with the cartridge casing is configured for use with a rifle having a bolt with a boss on the breech face that corresponds to the recessed primer.