Firearm Barrel Retaining System with Quick-Change Mechanism

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Solution Overview

Problem

Conventional barrel retaining systems for semi-automatic and automatic firearms are cumbersome and time-consuming, especially under combat conditions, as they require tools and partial disassembly of the handguard to swap barrels, and do not allow for quick change without affecting the point of aim.

Innovation Solution

A quick-change barrel retaining system where the barrel nut remains attached to the receiver and does not need to be removed to change barrels, using a dual or triple locking mechanism with splines and camming notches to secure the barrel independently of the receiver, allowing for tool-free barrel swapping without re-sighting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a conventional barrel nut retaining system is used, then the barrel is securely attached to the receiver, but the barrel swapping process becomes cumbersome and time-consuming requiring tools and partial disassembly

Engineering Contradiction:
Improvebarrel swapping speedVSAvoidretaining system structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The barrel extension is segmented into distinct functional zones: a tapered front portion for friction engagement, locking lugs for positive mechanical locking, and a rear portion for threading. This segmentation allows each zone to perform its specific function independently, enabling rapid barrel changes while maintaining secure attachment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The retaining system transitions from a static threaded connection to a dynamic multi-stage engagement process. The barrel extension first engages via tapered friction contact, then locks through rotating lugs that click into recesses, providing both speed and security in a sequential manner.

Inventive Principle:
Principle #15Dynamics

2Reliability

If a simple threaded connection is used between barrel and receiver, then the structure is simple, but the barrel becomes loose and unstable during firing

Engineering Contradiction:
Improvebarrel stabilityVSAvoidlocking mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The front portion of the barrel extension features a tapered conical surface that mates with a corresponding tapered surface in the receiver. This curved geometric interface provides friction-based alignment and stability during the engagement process, ensuring the barrel remains securely positioned.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The locking mechanism adds a rotational dimension to the otherwise linear threaded connection. The locking lugs rotate around the barrel axis to engage with recesses in the receiver, creating a multi-dimensional locking system that prevents both axial and rotational movement.

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

3Ease of operation

If the barrel nut is removed for barrel replacement, then the barrel can be easily detached, but the point of aim changes requiring re-sighting

Engineering Contradiction:
Improvebarrel detachment easeVSAvoidpoint of aim consistency
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The locking lugs and recesses are pre-configured in specific angular positions around the barrel extension. When the barrel is inserted and rotated, the lugs automatically align with and engage the recesses at predetermined orientations, ensuring consistent point of aim without requiring manual adjustment or re-sighting.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The barrel extension's tapered portion self-aligns with the receiver during insertion through friction engagement. The locking lugs then self-lock into the recesses through rotational engagement, automatically establishing the correct alignment and point of aim without external intervention.

Inventive Principle:
Principle #25Self-service

4Strength

If a barrel extension with locking lugs is used, then the barrel locks securely to the receiver, but the assembly process becomes more complex

Engineering Contradiction:
Improvebarrel-locking strengthVSAvoidmanufacturing complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The barrel extension integrates multiple functions into a single component: the tapered friction surface for alignment, the locking lugs for mechanical engagement, and the threaded rear portion for secure attachment. This merging reduces the total number of separate parts while maintaining strong locking capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The barrel extension serves multiple purposes simultaneously: it extends the barrel length, provides the locking interface through its lugs, enables threaded attachment to the receiver, and maintains the correct point of aim through its geometric design. This multi-functionality simplifies the overall assembly while ensuring strong attachment.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enables rapid and tool-free barrel changes without affecting the rifle's point of aim, reducing vibration and rattling, and maintaining headspacing consistency across different barrels.

Implementation Method 1

a third locking mechanism is provided by frictional engagement between the tapered contact surface on the barrel extension with the axial contact surface on top of each spline of the barrel nut

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

camming notches in the barrel locking lugs which translate rotational motion into axial displacement to tighten the locking engagement

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP2411756B1Firearm barrel retaining system
Publication Date: 2015.09.23 STURM RUGER & CO INC
  • EP2411756B1 patent drawingFigure 1
  • EP2411756B1 patent drawingFigure 2
  • EP2411756B1 patent drawingFigure 3

AI summary

A barrel retaining system for a firearm includes a firearm receiver having a barrel nut coupled thereto and a barrel assembly, which in one embodiment may include a barrel with a barrel extension coupled thereto. The barrel extension includes a plurality of barrel locking lugs that rotatably engage corresponding locking elements disposed on the barrel nut. The barrel extension may further include a flange that may engage one end of the locking elements of the barrel nut and the barrel locking lugs may engage an opposite end of the locking elements to wedge the locking elements therebetween for securing the barrel extension to the barrel nut. The firearm may be an autoloading rifle in some embodiments.