Magazine Spring Geometry for Rib Clearance and Higher Capacity
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Solution Overview
Problem
Existing firearms magazines face challenges in increasing capacity without increasing size, accommodating locating ribs for certain cartridges, and providing secure grip features, particularly in metal magazines.
Innovation Solution
A magazine spring with an increased coil length extending substantially the full magazine envelope and a narrowed waist portion to avoid interference with locating ribs, combined with a magazine tube featuring grip indentations for enhanced user grip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the spring is positioned rearward of the locating rib to accommodate blank cartridges, then the magazine can accommodate locating ribs for blank cartridges, but the spring length is reduced and magazine capacity is limited
Solution Approach 1:
The spring is divided into distinct functional segments: a head portion that engages the follower, a body portion with variable coil spacing that provides the necessary force, and a tail portion that engages the base plate. This segmentation allows the spring to be optimized for both locating rib accommodation and extended length to maximize magazine capacity.
Solution Approach 2:
The spring is designed to extend substantially the full forward-to-back dimension of the magazine envelope (at least 70%, preferably at least 85%), utilizing the longitudinal dimension of the magazine to increase capacity rather than occupying lateral space that would interfere with locating ribs.
2Quantity of substance
If the spring coil length is increased to extend full magazine envelope, then magazine capacity increases, but the spring may interfere with locating ribs
Solution Approach 1:
The spring exhibits local quality variations through different coil densities: tighter coil spacing in the body portion to generate necessary force, and adjusted spacing in the head and tail portions to clear locating ribs. This localized variation in coil density allows the spring to be long enough to maximize capacity while avoiding interference with locating ribs at critical locations.
Solution Approach 2:
The spring parameters are optimized including wire diameter (0.062-0.125 inches), mean coil diameter (0.5-1.5 inches), and variable pitch ratios to balance force generation with clearance for locating ribs. The variable pitch allows different sections of the spring to have different effective diameters, enabling it to navigate around locating ribs while maintaining sufficient length for high magazine capacity.
3Ease of manufacture
If conventional spring design is used with standard coil spacing, then manufacturing is simple, but the spring cannot achieve both full envelope extension and locating rib clearance
Solution Approach 1:
While maintaining manufacturability through standard spring manufacturing processes, the invention optimizes critical parameters including variable pitch ratios, wire diameter selections, and coil diameter variations to achieve both locating rib clearance and full envelope extension. These parameter adjustments are implemented within conventional manufacturing capabilities.
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 solution increases magazine capacity by 1-3 rounds and provides a secure grip, addressing the limitations of conventional magazines by enhancing coil efficiency and user interaction.
Implementation Method 1
A magazine spring is retained in the magazine tube in a somewhat compressed state between the baseplate and a follower, where the spring biases the follower, and any ammunition in the magazine, towards the feed lips at the upper end of the magazine tube.
Data Source
AI summary
A magazine spring includes intermediate coils each having a first end portion, a second end portion, and a waist portion between the first end portion and the second end portion. The waist portion has a width that is less than a width of at least one of the first end portion and the second end portion. A magazine tube is also disclosed. In one example, the magazine tube is made of sheet metal and includes grip indentations formed along forward corners of the magazine tube. The magazine tube may also define locating ribs for blank cartridges. A magazine spring having the narrow waist portion can be included in the magazine assembly so that the spring clears the locating ribs.