Fluted Boss Bolt Carrier for AR15 Water Drainage
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Solution Overview
Problem
The AR15/M16 series of firearms are prone to carrier tilt and malfunction in aquatic environments, requiring drainage of water before use, and have complex assembly requirements, which complicates over-the-beach operations and maintenance.
Innovation Solution
A bolt carrier assembly with an increased diameter boss, longitudinal flutes for water drainage, and a scallop cut for tool-free assembly, designed as a drop-in replacement for existing firearms, preventing carrier tilt and enabling immediate use in wet conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bolt carrier uses a conventional cylindrical design with lands and grooves, then the structure is simple and easy to manufacture, but carrier tilt occurs during operation causing wear to the receiver
Solution Approach 1:
The bolt carrier is segmented into distinct functional zones: a fluted boss portion at the rear, a transition zone, and a cylindrical portion with traditional lands and grooves at the front. This segmentation allows each zone to perform its specific function - the fluted boss prevents tilt while the cylindrical portion maintains compatibility with existing firearm mechanisms.
Solution Approach 2:
The bolt carrier transitions from a symmetric cylindrical design to an asymmetric fluted boss design. The flutes are arranged in a specific asymmetric pattern that creates stable contact points with the receiver, preventing the carrier from tilting during operation while maintaining structural integrity.
2Adaptability or versatility
If the firearm uses the AR15/M16 operating system, then it is widely used and standardized, but it cannot be fired when water is present in the operating system
Solution Approach 1:
The fluted boss design creates a porous-like structure with multiple channels and cavities that allow water to drain through the bolt carrier during operation. The flutes act as drainage pathways, preventing water accumulation that would otherwise cause malfunction, while maintaining the structural strength needed for reliable operation.
3Ease of operation
If the bolt carrier requires tool assembly and disassembly, then the structure can be optimized for performance, but it complicates over-the-beach operations and maintenance
Solution Approach 1:
The bolt carrier features a scallop cut at the rear that enables the charging handle to directly manipulate and remove the carrier without requiring additional tools. This self-service design allows soldiers to perform maintenance and conversions in the field immediately, without needing to stop and gather specialized tools.
4Reliability
If the boss diameter is increased to prevent carrier tilt, then carrier tilt is eliminated, but the bolt carrier size increases
Solution Approach 1:
Instead of simply increasing the boss diameter in one dimension, the design adds flutes that create vertical depth and complex geometry. This dimensional approach prevents carrier tilt through the fluted structure's contact points while maintaining an overall compact size that fits within existing firearm constraints.
Data Source
AI summary
An automatic rifle bolt carrier with a fluted boss for the AR15/M16 family of firearms has been provided. The rear of the bolt carrier has been provided with a boss having bearing surfaces which are in operational contact with the interior of the host firearm's upper receiver to prevent the carrier from tilting while it is reciprocating during normal operation. The boss and rearward end of the bolt carrier are provided with flutes which allow water to flow between the buffer tube and upper receiver while the bolt carrier is reciprocating during normal operation, enabling a properly equipped firearm to be used during over the beach operations. The bolt carrier also includes a scallop cut located about the top of its backmost end which is perpendicular to the longitudinal axis of the bolt carrier.