Quick barrel change firearm
Patent No. US9228786 (titled "Quick barrel change firearm") on Jan 13, 2012. The application was issued on Jan 5, 2016.
What is this patent about?
’786 is related to the field of firearm design, specifically focusing on modular weapon systems capable of sustained high rates of fire. In automatic and semi-automatic platforms, barrel overheating and maintenance complexity often limit operational reliability. The invention addresses these challenges by introducing a structural architecture that facilitates rapid field maintenance and enhances mechanical stability during thermal expansion.
The underlying idea behind ’786 is the use of a structural backbone that serves as the primary guide for the bolt carrier while providing a precision mounting interface for a quick-change barrel. By decoupling the bolt carrier’s guidance from the lower receiver and utilizing a swinging wedge mechanism to lock the barrel, the system ensures that the barrel is pulled into self-aligning V-blocks. This geometry maintains a consistent zero even as the barrel expands radially and longitudinally due to extreme heat.
The claims of ’786 focus on a firearm assembly comprising a bolt carrier guided by a backbone, a lower receiver, and a specialized barrel retention system. Central to the independent claims is the swinging wedge which engages a cross pin on the barrel to draw it upward into V-blocks and lock a barrel extension flange into a corresponding groove. This specific mechanical linkage ensures the barrel is centered and secured against fore-and-aft movement relative to the backbone.
In practice, the invention simplifies manufacturing and maintenance through a drop-in trigger block assembly that can be fully built outside the firearm and simply pinned into the lower receiver. The gas system is similarly optimized for longevity by moving the metering function from the barrel’s gas port to a separate, adjustable metered gas port in the gas block. This prevents the common issue of cyclic rate increases caused by the erosion and enlargement of the barrel's internal gas orifice over time.
The system differentiates itself from prior art by its unique bolt carrier geometry and safety features. The bolt carrier features a narrow waist that slides through a slot in the backbone, allowing the upper portion to be guided internally while the lower portion remains external. Furthermore, a safety bar prevents the firearm from being disassembled when the main spring is compressed, and an integrated anti-bounce weight within the spring guide ensures reliable ignition by preventing the bolt from rebounding during high-speed cycling.
How does this patent fit in bigger picture?
Technical Landscape
In the early 2010s when ’786 was filed, automatic and semi-automatic firearm architectures were typically implemented using fixed barrel assemblies that required significant downtime and specialized tools for replacement. At a time when high-capacity magazines were becoming standard, thermal management commonly relied on passive cooling rather than modular component exchange, which made sustained fire non-trivial due to the risk of barrel deformation or premature cartridge detonation. Furthermore, internal cycling components like bolt carriers and gas pistons were generally constrained by the dimensions of the upper receiver, often leading to mechanical interference or reliability issues when subjected to the heat and fouling of high-cyclic rates.
Prosecution Position
The disclosed invention represents a meaningful technical advancement through an architectural shift in barrel retention and internal component management. By integrating a swinging wedge and barrel latch mechanism, the system enables a rapid-change barrel capability that maintains precise centering via V-block alignment while accommodating longitudinal and radial thermal expansion through a spring-loaded yoke. Additionally, the invention overcomes reliability constraints by utilizing a backbone structure that guides the bolt carrier independently of the lower receiver and employs a metered gas port located away from the barrel to ensure consistent cycling pressure even as the primary gas port erodes. These features collectively enable sustained high-volume fire while mitigating the risks of mechanical failure and accuracy loss associated with extreme thermal stress.
Claims
This patent contains 22 claims, including independent claims 1, 4, and 15, which focus on the structural architecture of a firearm featuring a backbone guide for a bolt carrier, a modular lower receiver, and a specialized barrel attachment system utilizing a swinging wedge and cross pin to secure the barrel extension. Independent claim 1 provides a comprehensive assembly including a gas piston, trigger block, and various safety and cycling mechanisms, while claims 4 and 15 specifically emphasize the mechanical interface between the barrel, v-blocks, and the backbone. The dependent claims serve to further define the geometry and movement of the bolt carrier within the backbone slot, specify the use of a U-shaped yoke for thermal expansion management, and detail the integration of cam pins, hammer assemblies, and firing pin configurations for fully automatic operation.
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US9228786
- Application Number
- US13350156A
- Filing Date
- Jan 13, 2012
- Publication Date
- Jan 5, 2016
- External Links
- Slate, USPTO , Google Patents