Straight-Pull Bolt With Sliding Breech-Block Locking
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Solution Overview
Problem
Existing straight-pull bolt mechanisms in repeating rifles, particularly shotguns, require complex manipulation and significant physical effort, and pose safety risks due to their open design and reliance on gas pistons, making them unsuitable for conventional repeating shotguns.
Innovation Solution
A straight-pull bolt mechanism for repeating shotguns that utilizes a breech block mounted for sliding movement within receiver grooves, with a breech lock and striker design that allows for easy operation and safety features like a split striker and rear-closed receiver, eliminating the need for gas pistons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sliding-rotary bolt mechanism is used in repeating rifles, then the bolt can be locked against the firing mechanism, but the bolt handle requires complex manipulation and longer operation time
Solution Approach 1:
The bolt mechanism is divided into separate functional components: the bolt body with locking lugs for reliable locking, and a independently operable bolt handle that pivots on a pin. This segmentation allows the bolt to move straight back and forth without complex rotary motion, simplifying manipulation while maintaining locking capability through the dedicated locking lugs engaging with locking surfaces in the receiver.
Solution Approach 2:
Instead of rotating the entire bolt assembly as in traditional mechanisms, the invention inverts the approach by having the bolt move linearly while a separate handle pivots independently. The handle connects to the bolt body and transfers rearward motion to unlock and eject, then forward motion to lock and chamber. This inversion of the traditional rotary-bolt concept eliminates complex trajectories while preserving reliable locking.
2Reliability
If a sliding-rotary bolt mechanism is used in repeating rifles, then the bolt can lock against the firing mechanism, but the operation requires significant physical strength
Solution Approach 1:
The bolt mechanism incorporates dynamic elements including a spring-loaded extractor that automatically engages cartridge cases, and a bolt handle with pivoting motion that leverages mechanical advantage. The extractor spring provides continuous pressure to secure cartridges, while the pivoting handle reduces the force needed to operate the bolt by converting linear motion into rotational leverage at the pivot point.
Solution Approach 2:
The invention introduces intermediary components between the operator and the bolt: a pivoting handle that acts as a lever to reduce operating force, and a spring-loaded extractor that mediates the engagement between bolt and cartridge. These intermediaries translate small operator inputs into effective bolt operation without requiring significant physical strength, while maintaining reliable locking through the direct engagement of locking lugs with receiver surfaces.
3Ease of operation
If the bolt mechanism is open towards the rear, then the bolt can be operated, but the bolt may fly backwards during malfunction and cause injury
Solution Approach 1:
The receiver is designed with a closed rear end that prevents the bolt from flying backward during malfunctions. This preliminary protective structure counteracts the potential harmful effect of bolt recoil before it can injure the shooter. The closed receiver maintains bolt accessibility for operation while providing inherent safety by containing any backward movement within the receiver boundaries, eliminating the need for additional safety mechanisms.
4Productivity
If a gas piston is used to control bolt movement, then the bolt can be automatically loaded, but the mechanism becomes complex and unsuitable for conventional repeating shotguns
Solution Approach 1:
The invention extracts the gas piston system from the bolt mechanism, removing the complex automatic loading components that make the system unsuitable for conventional repeating shotguns. Instead, a simplified manual bolt operation is implemented where the shooter directly controls bolt movement, eliminating gas pistons, springs, and automatic cycling mechanisms while maintaining adequate loading speed for shotgun applications.
Solution Approach 2:
The design favors simpler, more robust components over complex precision mechanisms. Rather than using expensive gas pistons and automatic loading systems, the invention employs straightforward manual operation with basic mechanical elements that are easier to manufacture, maintain, and repair. This approach prioritizes reliability and adaptability for conventional shotguns over maximum automatic loading speed.
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
The straight-pull bolt mechanism of a repeating rifle has a bolt (3) which is mounted with the possibility of sliding movement in the guide grooves (38) of the bolt (3) receiver (1). The breech block (4) is mounted with the possibility of sliding movement above the bolt (3), with the rear part of the breech block (4) being mounted in the guide grooves (38) of the bolt (3) receiver (1). The front part of the breech block (4) is movably connected to the upper part of the bolt (3); furthermore the front part of the breech block (4) is provided with at least one locking lug (24) for locking the breech block (4) in the locked position of the bolt (3); and furthermore the front part of the breech block (4) is provided with a puller (7) extensible in the unlocked position of the bolt (3) over the front edge of the bolt (3). The breech lock (5) is provided with a cross pin (26), the ends of which engage with the front brackets (25) arranged oppositely in the breech block (4). The repeating rifle has a groove (39) above the chamber (34) for the locking lug (24) of the breech block (4).