M240 Rifle Select Fire Trigger Assembly
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Solution Overview
Problem
Existing M240 rifles lack a selective mechanism to easily switch between fully automatic and semi-automatic firing modes, with previous conversion methods being permanent and not allowing for easy reversal.
Innovation Solution
A trigger assembly with a select fire mechanism, including a sear, disconnector, and external switch, allows the rifle to be selectively operated in fully automatic or semi-automatic modes by altering the engagement of the sear with the op rod assembly through a selector body with different selector surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a permanent conversion method is used to convert M240 rifles to semi-automatic fire, then the rifle can be operated semi-automatically, but the conversion cannot be reversed and requires permanent modifications
Solution Approach 1:
The patent applies the dynamics principle by creating a selectable firing mode mechanism that allows the rifle to dynamically switch between semi-automatic and fully-automatic modes. The select fire mechanism includes a switchable component that can be positioned to engage different firing modes, making the system adaptable rather than fixed. This resolves the contradiction by enabling reversible conversion without permanent modifications.
Solution Approach 2:
The patent implements multi-functionality through the select fire mechanism that integrates both semi-automatic and fully-automatic firing capabilities into a single rifle system. The mechanism allows one rifle to perform multiple firing functions depending on the selected mode, eliminating the need for separate rifles or permanent conversions for different firing modes.
2Adaptability or versatility
If a select fire mechanism is added to allow switching between firing modes, then firing mode flexibility is improved, but device complexity increases
Solution Approach 1:
The patent applies the merging principle by integrating the select fire mechanism directly into the existing trigger assembly. The switchable component is combined with the trigger mechanism, sear, and disconnector elements, allowing the firing mode selection to be achieved through modification of existing components rather than adding entirely separate systems. This reduces overall device complexity while maintaining firing mode flexibility.
Solution Approach 2:
The patent uses an intermediary approach by introducing a switchable component that acts as a mediator between the trigger mechanism and the firing system. This intermediary element selectively engages or disengages specific components (such as the disconnector or sear) to enable or disable automatic fire, providing a simple control mechanism without requiring complex reconfiguration of the entire firing system.
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 the M240 rifle to be easily switched between fully automatic and semi-automatic firing modes, providing flexibility without the need for permanent modifications, allowing for single-shot or continuous firing based on user preference.
Implementation Method 1
A disconnector spring biases the disconnector toward the sear and the selector body
Implementation Method 2
A sear spring of the trigger assembly biases the sear to pivot to position the sear tip in the path of the op rod assembly
Implementation Method 3
Expanding gases from the ignition of powder in the cartridge furnishes the energy for the operation or cycling of the rifle. Immediately after firing, as the bullet traverses the barrel and passes an internal gas port prior to exiting from the muzzle, the live gases expand through the gas port into the gas tube or cylinder to impinge against the head of a piston
Data Source
AI summary
A trigger assembly for a trigger housing for an M240 Assault Rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.