Firearm Magazine Accordion Spring and Tilting Follower Design

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Solution Overview

Problem

Conventional box-type magazines for long guns have a large profile and project below the stock, interfering with handling and lacking a compact design while maintaining cartridge capacity, and they often experience feeding issues such as jams.

Innovation Solution

A compact, low-profile magazine design featuring a unique accordion-type main spring and a tilting follower with a contoured cartridge support surface, allowing for a vertical double/staggered stack arrangement and smooth cartridge feeding, with a floor plate that is detachably secured to the magazine housing for enhanced functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a conventional box-type magazine is used to hold cartridges, then the magazine has sufficient cartridge capacity, but the magazine projects a significant distance below the stock and interferes with handling

Engineering Contradiction:
Improvecartridge capacityVSAvoidhandling
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The follower is designed to tilt dynamically during operation. It pivots about a lateral axis defined by guide bosses, transitioning between horizontal and angled positions as cartridges are fed. This dynamic movement allows the follower to adapt to cartridge discharge while maintaining a compact magazine profile that sits flush with the stock.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The magazine utilizes a vertical double/staggered stack arrangement where cartridges are positioned in two vertical columns with alternating offsets. This three-dimensional stacking configuration maximizes cartridge capacity within a compact volume, allowing the magazine to hold multiple rounds without projecting below the stock.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of operation

If a compact magazine design is implemented to reduce profile, then handling is improved, but cartridge feeding reliability may be compromised

Engineering Contradiction:
ImprovehandlingVSAvoidcartridge feeding
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The follower features a contoured cartridge support surface with curved geometry rather than flat surfaces. This contoured design positively guides cartridges during the tilting motion, ensuring smooth feeding action and preventing hang-ups or jams despite the compact magazine size.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The tilting follower mechanism creates dynamic feeding action that adapts to cartridge positioning. As the follower tilts between horizontal and angled positions, the contoured surface maintains continuous contact with cartridges, providing positive feeding guidance throughout the motion cycle and ensuring reliable operation.

Inventive Principle:
Principle #15Dynamics

3Extent of automation

If a spring mechanism is used to bias the follower upwards, then cartridge dispensing is automated, but the spring increases the magazine profile when compressed

Engineering Contradiction:
Improvecartridge dispensingVSAvoidmagazine profile
Core Design Contradiction:
Extent of automationVSLength of stationary object

Solution Approach 1:

The main spring is configured with folding features that allow it to compress to a compact size. When fully compressed, the spring maintains an accordion-like folded structure that minimizes its length in the vertical direction, enabling the magazine to achieve a low profile while still providing the necessary biasing force for automated cartridge dispensing.

Inventive Principle:
Principle #15Dynamics

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

The design achieves a flush fit with the firearm stock, reducing the magazine's profile without sacrificing capacity, and ensures reliable and jam-free cartridge feeding, improving handling and operation.

Implementation Method 1

a compressible main spring disposed in the cavity; an elongated follower disposed in the cavity and biased in an upwards direction by the main spring

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP3821197B1Magazine for firearm
Publication Date: 2025.01.15 STURM RUGER & CO INC
  • EP3821197B1 patent drawingFigure 1
  • EP3821197B1 patent drawingFigure 2
  • EP3821197B1 patent drawingFigure 3

AI summary

A magazine for a firearm such as long guns comprises a housing defining a cavity for holding a double staggered stack of cartridges and spring-biased tillable follower for dispensing the cartridges into the action of the firearm. Features include an accordion type flat spring specially configured to fold into a flat condition in which adjacent bends of the spring are arranged side- by-side to reduce the folded height of the spring. The follower includes bosses slideable in mating vertical housing slots to guide the follower upward/downward motion and allow front to rear tilting action. A coupling mechanism includes a plurality of interlocking mounting teeth forming a selectively interlocked arrangement for detachably assembling the floor plate to magazine housing. A resilient snap fit tab on the floor plate secures the coupling. The magazine is longitudinally elongated and configured to fit flushly with the underside of the firearm when mounted.