Prior art

Analysis of Prior Art for U.S. Patent No. 9,151,557

An analysis of the prior art cited during the prosecution of U.S. Patent No. 9,151,557, "Automatic sear assembly for a rifle," reveals several key patents that define the technological landscape at the time of the invention. This analysis examines the most relevant of these, detailing their contributions and assessing their potential to anticipate the claims of the '557 patent.

Key Prior Art and Potential Anticipation

The following prior art references were considered significant during the examination of the '557 patent. Each is evaluated for its relevance to the independent claims of the '557 patent.

1. U.S. Patent No. 4,441,403 (Schillstrom)

• Publication Date: April 10, 1984
• Filing Date: June 1, 1981
• Title: Sear for automatic firearm
• Brief Description: Schillstrom discloses an automatic sear for a firearm that includes a body with a bore for a pivot pin and an actuating arm. The sear is designed to be tripped by the bolt carrier of the firearm to effect automatic fire.
• Potential Anticipation: This patent is broadly relevant to the concept of an automatic sear. However, it does not disclose the specific combination of an independent sear lever with bidirectional articulation, biased by a separate spring, all sharing a common rotational axis with the sear and a second spring for the selector switch, as claimed in Claim 1, 16, and 20 of the '557 patent. Schillstrom's design is a more unitary sear structure.

2. U.S. Patent No. 4,663,875 (In-Kun)

• Publication Date: May 12, 1987
• Filing Date: October 28, 1985
• Title: Automatic sear for a firearm
• Brief Description: In-Kun describes an automatic sear mechanism for a firearm that is designed for compactness and reliability. It features a sear that is actuated by the bolt carrier to release the hammer for automatic firing.
• Potential Anticipation: Similar to Schillstrom, In-Kun's invention is in the field of automatic sears. While it addresses the general function of an automatic sear, it lacks the specific arrangement of a separate, spring-biased sear lever that can move independently in one direction and engage the sear in another, all on a shared axis. Therefore, it does not appear to anticipate the novel combination of elements in Claims 1, 16, and 20.

3. U.S. Patent No. 7,293,385 (McCormick)

• Publication Date: November 13, 2007
• Filing Date: May 21, 2002
• Title: Modular trigger group for firearms and firearm having a modular trigger group
• Brief Description: McCormick discloses a modular trigger assembly where the trigger, hammer, and disconnector are contained within a single housing that can be "dropped in" to the receiver of a firearm. This design aims to improve the consistency and quality of the trigger pull.
• Potential Anticipation: This patent is relevant in the context of firearm trigger mechanisms. However, its focus is on the modularity of the entire fire control group. It does not describe or suggest the specific automatic sear assembly with a bidirectionally articulating sear lever as detailed in the '557 patent. The core inventive concept of the '557 patent, which is the interaction between the sear, a separate sear lever, and the associated springs on a common axis for selective fire in large-bore rifles, is not present in McCormick. Thus, it does not anticipate Claims 1, 16, or 20.

4. U.S. Patent Application Publication No. 2009/0282980 A1 (Kincel et al.)

• Publication Date: November 19, 2009
• Filing Date: May 15, 2008
• Title: Firearm with ambidextrous safety and selector
• Brief Description: This application describes a firearm with an ambidextrous safety and selector mechanism. It details the interaction of the selector with the trigger mechanism to switch between safe, semi-automatic, and automatic firing modes.
• Potential Anticipation: While this application discusses the safe/fire selector switch and its interaction with the fire control group, it does not disclose the specific automatic sear assembly of the '557 patent. The key elements of the separate, spring-loaded sear lever with its unique bidirectional movement on a shared axis with the sear are absent. Therefore, it does not anticipate Claims 1, 16, and 20.

5. U.S. Patent Application Publication No. 2011/0138981 A1 (Dueck et al.)

• Publication Date: June 16, 2011
• Filing Date: October 18, 2010
• Title: Firearm with Improved Fire Control System
• Brief Description: Dueck et al. disclose an improved fire control system for a firearm, focusing on the geometry and interaction of the hammer, trigger, and disconnector to provide a better trigger feel and more reliable operation.
• Potential Anticipation: This application is focused on the refinement of the primary trigger and hammer engagement. It does not teach or suggest the novel automatic sear and sear lever combination for enabling automatic fire in the manner described by the '557 patent. The concept of a separate, bidirectionally articulating sear lever is not present, and therefore it does not anticipate Claims 1, 16, and 20.

In summary, while the cited prior art relates to firearm trigger mechanisms and automatic sears, none of the references individually or in combination appear to disclose all the elements of the independent claims of US Patent 9,151,557. The novelty of the '557 patent resides in the specific mechanical arrangement of the automatic sear, the independently rotating sear lever, and the two springs all sharing a common axis, which provides a unique solution for enabling selective fire in large-bore rifles.