Rotary Delayed Blowback Bolt Mechanism for Recoil Attenuation
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Solution Overview
Problem
Existing firearm designs, particularly AR-15/M4 carbines with gas impingement driven action assemblies, face challenges in effectively attenuating recoil forces during cartridge discharge, leading to increased felt recoil and muzzle climb.
Innovation Solution
A rotary delayed blowback assembly is introduced, featuring chamfered or angled profiles on bolt locking lugs and trunnion grooves within the upper receiver or barrel extension, which absorb recoil forces through radial delay and attenuation, allowing the bolt to counter-rotate and unlock before full unseating, reducing the impact of recoil on the firearm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional direct blowback or gas impingement systems are used, then the firearm can cycle cartridges reliably, but the recoil forces are transmitted directly to the receiver causing increased felt recoil and muzzle climb
Solution Approach 1:
The bolt assembly is segmented into a bolt body with locking lugs and a separate carrier, allowing the bolt to rotate independently within the carrier. This segmentation enables the locking lugs to engage and disengage from the receiver grooves through rotation rather than direct linear movement, delaying and attenuating recoil force transmission to the receiver.
Solution Approach 2:
The locking lugs are preliminarily positioned to engage the receiver grooves before full cartridge discharge occurs. The chamfered surfaces are pre-configured to guide the bolt rotation that will occur during recoil, allowing the system to prepare for and manage the recoil forces before they fully develop, thereby reducing the impact on the receiver.
2Force
If the bolt rotates to unlock during recoil, then recoil forces are attenuated, but the timing and precision of the rotation must be precisely controlled to ensure proper cycling
Solution Approach 1:
The locking lugs and receiver grooves feature localized chamfered surfaces at specific angles and positions. These localized geometric features create a predetermined rotation path and timing, ensuring that the bolt rotates at the correct moment during recoil while maintaining precise engagement. The chamfers are strategically placed to guide rotation without requiring high precision throughout the entire lug-groove interface.
3Force
If the bolt carrier group mass is increased to reduce recoil, then recoil attenuation improves, but the weight of the firearm increases
Solution Approach 1:
The bolt assembly is designed to rotate dynamically within the carrier during recoil rather than moving purely linearly. This rotational degree of freedom allows the same mass to more effectively manage recoil forces through the rotational inertia and the delayed engagement mechanism, reducing the need to increase mass for recoil control.
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 significantly reduces felt recoil and muzzle climb by absorbing recoil forces during the unseating process, maintaining sufficient recoil for proper cycling and cartridge chambering, while enhancing the overall handling and accuracy of the firearm.
Implementation Method 1
a rotational inducing profile established between bolt lugs and a mating receiving pattern within the upper receiver or a trunnion installed within the receiver
Data Source
AI summary
A delayed rotary blowback mechanism integrated into a firearm bolt and carrier subassembly. A plurality of radial locking lugs are configured at a rear end of the bolt and seat within a mating profile of an upper receiver interior or integrated trunnion in a fully chambered position. A plurality of chamfered locations are configured between the lugs and a receiving profile in the barrel or trunnion for influencing linear to rotational motion of the bolt. A cam pin extends upwardly from the bolt and seats through a circumferentially directed slot configured within the bolt carrier. Upon initiating of the discharge cycle, signaled by the round traveling through and out the end of the barrel, the chamfered configuration results in the bolt and cam pin rotating within the carrier and the lugs subsequently separating from the receiver or trunnion, with the bolt and associated carrier retaining sufficient inertia to cycle through the discharge cycle to the set position concurrent with reloading a subsequent cartridge.