Delayed Blowback Device for AR15 Rifle Bolt Carrier
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Solution Overview
Problem
Current firearms operating systems for AR15 type rifles chambered in pistol calibers, such as direct blowback, radial delayed blowback, and roller delayed blowback, do not offer a solution for varying the time between firing rounds effectively, and existing technologies are either expensive or heavy, lacking a cost-effective and lightweight option.
Innovation Solution
A delayed blowback device utilizing a bolt, gas key, and spring-loaded projection, where the spring-loaded projection is retained in the gas key or on the bolt, allowing for adjustable delay by changing the spring or using a slide stop, enabling variation of the time between firing rounds by modifying the spring rate or distance, thus controlling the bolt carrier return speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct blowback system is used with heavy BCG and added weights, then reliability is improved, but weight increases and recoil increases
Solution Approach 1:
The patent changes the mass parameter of the BCG by removing heavy components (weights, buffers) and instead uses a gas pressure regulation mechanism to control bolt carrier speed. The gas key with adjustable orifice modifies the gas pressure parameter acting on the BCG, allowing reliable operation with a lighter BCG mass.
2Object-generated harmful factors
If radial delayed blowback is used with separate bolt and carrier, then recoil is reduced, but manufacturing cost increases
Solution Approach 1:
The patent makes the BCG universal by maintaining the traditional AR-15 integrated bolt-carrier design that can be used in both rifle and pistol caliber configurations. The gas key assembly with adjustable orifice provides the delayed blowback function previously requiring a specialized radial delayed blowback BCG, thus eliminating the need for expensive custom-machined components while achieving similar recoil reduction.
3Object-generated harmful factors
If roller delayed blowback system is used with rollers, then recoil is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the delayed blowback function from complex mechanical components (rollers, cam pockets) and implements it through a simpler gas pressure regulation system. The gas key with adjustable orifice isolates and controls the gas pressure parameter, providing the necessary delay without requiring additional moving parts, cam mechanisms, or tight tolerance components.
4Productivity
If gas key with spring-loaded projection is used, then firing rate control is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic firing rate control through an adjustable gas orifice that can be changed based on desired operation. The spring-loaded projection with cam mechanism provides dynamic adjustment capability, allowing the operator to optimize the gas pressure regulation for different firing scenarios (semi-auto, full-auto, different calibers) without increasing permanent device complexity.
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 allows for adjustable firing rates by changing the spring or using a slide stop, providing a cost-effective and lightweight option that reduces recoil and allows for interchangeable upper receivers, enhancing the operational efficiency of AR15 type rifles.
Implementation Method 1
A delayed blowback device includes a bolt, a gas key and a spring-loaded projection
Implementation Method 2
The gas key is attached to a top of the bolt. The gas key controls gas flow to regulate bolt carrier return speed
Implementation Method 3
The cam pocket will act as a locking point for the spring-loaded projection when the bolt is in battery
Implementation Method 4
The projection contacts a rear surface of the cam pocket. Friction provides resistive force during bolt movement
Data Source
AI summary
A delayed blowback device preferably includes a bolt, a gas key and at least one spring-loaded projection. A projection slot or projection pocket traverses a bottom of the gas key, which are sized to receive a width of the spring-loaded projection. The spring-loaded projection could have a round outer perimeter or a D-shaped outer perimeter. A location of the projection slot along a length of the gas key is such that the projection contacts a cam pocket in an inner wall of an upper receiver. In a second embodiment, a slide stop in a bottom of the gas key is used to push a projection into the cam pocket. Spring rates may be varied to increase or decrease the firing rate of the firearm. The return speed of the bolt carrier could also be modified by changing a distance between the projection pocket and a rear of the bolt.