Firearm Hammer Extended Surface Bolt Carrier Travel

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Solution Overview

Problem

Firearms using the Stoner Pattern, such as AR-15 and variants, face limitations in bolt catch clearance, leading to reduced bolt carrier travel and increased failure rates, especially with longer cartridges, due to the narrow gap between bolt lugs and the bolt catch, which restricts efficient operation and reliability.

Innovation Solution

The design enhances bolt carrier travel by increasing the clearance between the bolt lugs and the bolt catch through modifications such as shortening the bolt carrier, gas key, and buffer tube lengths, and adding additional vent holes to reduce the effective piston stroke length, allowing for greater rearward movement of the bolt carrier without jamming, and incorporating an extended hammer surface to contact the bolt carrier, thereby increasing the bolt catch overtravel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the bolt carrier length is shortened to increase bolt catch clearance, then the bolt carrier travel is improved, but the structural strength and durability may be compromised

Engineering Contradiction:

Improvebolt carrier travel distanceVSAvoidbolt carrier structural strength

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The bolt carrier is segmented into functional zones: a shortened travel portion that clears the bolt catch, and a reinforced structural portion that maintains strength. The extended hammer surface acts as a separate structural element that provides additional bearing surface without increasing overall bolt carrier length.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bolt carrier assembly uses composite construction with the bolt carrier, gas key, and buffer tube working together as an integrated system. The extended hammer surface made of hardened steel provides additional structural support and bearing surface where the bolt carrier travels rearward.

Inventive Principle:

Principle #40Composite materials

2Length of moving object

If the gas key and buffer tube lengths are shortened to increase clearance, then the bolt carrier overtravel is improved, but the gas sealing and recoil management may be affected

Engineering Contradiction:

Improvebolt carrier rearward travelVSAvoidgas sealing and recoil management

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The gas key length and buffer tube length are optimized to specific parameters that balance clearance requirements with functional performance. Additional vent holes are strategically positioned to maintain gas sealing while allowing controlled pressure release during operation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The extended hammer surface acts as an intermediary element that provides a bearing surface for the bolt carrier during rearward travel. This mediator allows the bolt carrier to travel further without directly contacting and potentially damaging the bolt catch or receiver interior surfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If additional vent holes are added to reduce effective piston stroke, then the bolt carrier jamming is reduced, but the gas pressure control and power may be compromised

Engineering Contradiction:

Improvebolt carrier operation reliabilityVSAvoidgas pressure and firing power

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

Vent holes are strategically positioned in specific locations on the gas key and bolt carrier where they provide jam prevention without significantly compromising overall gas pressure. The local quality of gas flow is optimized at different points in the system to balance reliability and power.

Inventive Principle:

Principle #3Local quality

4Length of moving object

If the extended hammer surface is added to contact the bolt carrier, then the bolt catch clearance is improved, but the device complexity increases

Engineering Contradiction:

Improvebolt catch clearance distanceVSAvoidtrigger assembly complexity

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The extended hammer surface serves multiple functions: it provides the bearing surface for increased bolt carrier clearance, acts as a structural reinforcement element, and maintains the cocking function of the hammer. This multi-functional design adds clearance capability without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11530889B1Firearm, trigger assembly, and trigger assembly hammer

Publication Date: 2022.12.20 FCIP LLC

AI summary

A hammer usable with a firearm having a bolt carrier that is configured to travel forward and rearward within the firearm during a firing operation of the firearm. The hammer includes a mounting portion configured to rotatably constrain the hammer within the firearm and a firing pin contact portion configured to rotate upward to a vertical most position and contact a firing pin. The hammer further includes a sear notch configured to contact a trigger, and an extended surface that is configured to contact a bottom portion of the bolt carrier when the bolt carrier travels in a rearward direction after firing of the firearm. The extended surface allows for additional travel of a bolt carrier group of the firearm.