Adjustable Forend Guide for Pump Action Firearm Barrel Fit
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Solution Overview
Problem
Mossberg pump action shotguns require different forends for barrels with varying diameters to maintain a close tolerance and prevent rotational movement, leading to the need for multiple forend designs, which can result in a sloppy feel during use.
Innovation Solution
A forend with a U-shaped cross-section and a cylindrical frame that includes multiple guides with distinct barrel receptacles, allowing selection of a guide to match the barrel diameter, preventing axial rotation by keyed engagement, and secured by an action slide cap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single forend design is used with barrels of varying diameters, then the device complexity and number of parts are reduced, but the manufacturing precision and fit tolerance between the forend and barrel deteriorate
Solution Approach 1:
The guide is divided into multiple segments or positions along its length, with each segment having a different receptacle configuration for engaging barrels of different diameters. This segmentation allows a single foreend to accommodate multiple barrel sizes while maintaining proper fit tolerance through the keyed engagement at the appropriate segment position.
Solution Approach 2:
The guide is made adjustable or movable within the foreend body, allowing it to be positioned at different locations along the foreend axis. This dynamic positioning enables the keyed engagement feature to align with barrels of varying diameters, maintaining manufacturing precision without requiring multiple fixed foreend designs.
2Manufacturing precision
If multiple distinct forends are provided for different barrel diameters, then the manufacturing precision and fit tolerance are maintained, but the device complexity and variety of parts increase
Solution Approach 1:
The guide is designed with multi-functionality to perform the same keyed engagement function for barrels of different diameters. By incorporating multiple receptacle configurations or adjustable positioning capabilities, a single guide component replaces multiple specialized guides, reducing device complexity while maintaining manufacturing precision.
Solution Approach 2:
The guide contains nested or integrated features that allow it to adapt to different barrel diameters. The keyed engagement mechanism is nested within the guide structure in a way that permits adjustment or selection of the appropriate engagement point for each barrel size, eliminating the need for separate foreend variants.
3Ease of operation
If the forend is loosely fitted to the barrel, then ease of assembly is improved, but rotational movement of the forend about the magazine tube increases
Solution Approach 1:
The keyed engagement feature automatically performs the function of preventing rotational movement without requiring additional adjustment or assembly steps. The key and receptacle geometry is designed to self-align and self-lock, providing rotational stability as part of the basic assembly process rather than requiring separate stabilization mechanisms.
4Stability of the object's composition
If close tolerance is maintained between the forend and barrel, then rotational movement is limited, but the device complexity increases due to the need for precise manufacturing
Solution Approach 1:
The keyed engagement feature uses simple, easily manufactured geometric shapes (key and receptacle) that can be produced with standard tolerances. Rather than requiring complex precision machining throughout the foreend, the rotational stability is achieved through these simple, low-cost keyed features that are straightforward to manufacture and inspect.
Data Source
AI summary
A forend for use with a pump action firearm having a barrel with a magazine tube arranged adjacent and parallel thereto. The pump action firearm further includes an action slide assembly slidably receiving the magazine tube and the action slide assembly has a distal end and an action slide cap configured to engage the distal end of the action slide assembly. The forend comprises an elongate body having a U-shaped cross-section configured to be secured to the action slide assembly by an action slide cap engaged to a distal end of the action slide assembly. A guide defining a barrel receptacle is configured for keyed engagement to an interior of the elongate body to prevent rotational movement of the guide relative to the elongate body with the barrel receptacle facing toward the top of the U-shaped cross-section of the body. The barrel receptacle is configured to nest a radial portion of a barrel exterior, wherein the guide limits axial rotation of the forend about the magazine tube relative to the barrel.