Firearm Bolt Carrier Shield for Ejection Port Debris Protection
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Solution Overview
Problem
Firearms are susceptible to fouling due to debris entering the ejection port, particularly in stressful situations where users may fail to manually close the ejection port door, leading to potential jamming or failure.
Innovation Solution
A shield mechanism affixed to the bolt carrier automatically blocks the ejection port during firing, sliding away from the port during the rearward movement to prevent debris from entering and fouling the firing components, reducing frictional wear and eliminating the need for manual door closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a manual ejection port door is used to block debris, then the ejection port can be covered to prevent fouling, but the user may fail to close it during stressful situations leading to jamming
Solution Approach 1:
The shield is automatically actuated by the bolt carrier's rearward movement to block the ejection port, eliminating the need for manual user action. The system serves itself by using the existing cyclic motion of the bolt carrier to operate the protective shield, ensuring consistent debris prevention without relying on user behavior during stressful situations.
Solution Approach 2:
The shield blocks the ejection port in advance during the bolt carrier's rearward movement, before debris can enter the receiver. This preliminary protective action occurs automatically as part of the normal cycling sequence, preventing fouling before it can occur rather than requiring corrective manual intervention.
2Ease of operation
If the ejection port is left open for easy operation, then the user can quickly access components, but debris enters the receiver and fouls the firing components
Solution Approach 1:
The shield acts as an intermediary barrier between the ejection port and the receiver's firing components. It selectively blocks debris while allowing the ejection port to remain structurally open for its intended functions, preventing harmful factors from reaching the vulnerable firing components without requiring the port itself to be closed.
3Reliability
If a cover plate is made to move independently of the bolt assembly to block the ejection port, then debris prevention is improved, but frictional wear increases and component failure becomes more likely
Solution Approach 1:
The shield is merged with the bolt carrier through longitudinal affixing, creating a single integrated moving unit. This combination eliminates the need for independent movement mechanisms and multiple friction interfaces, reducing wear and complexity while maintaining effective ejection port protection through the unified structure's coordinated motion.
Data Source
AI summary
The present invention provides for a firearm having a receiver defining a bore with the receiver extending along a longitudinal axis. The receiver defines an ejection port transverse to the longitudinal axis with the bore defining an inner surface. The firearm further includes a bolt carrier disposed in the bore and moveable relative to the receiver along the longitudinal axis between a firing position and a rearward position. The firearm also includes a shield longitudinally affixed to the bolt carrier and movable with the bolt carrier as a unit between the firing and rearward positions along the longitudinal axis with the shield blocking the ejection port when in the firing position and the shield sliding along the inner surface away from the ejection port when moving to the rearward position in conjunction with the bolt carrier.