# US 10,371,475 B2 · Firearm magazine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,475 B2 - Document ID: US10371475B2 - Status: Granted - Kind: B2 - Application number: 15/710,600 - Filed: 2017-09-20 - Published: 2018-03-22 - Granted: 2019-08-06 - Earliest claimed: 2016-09-21 - Assignees: Browning - Applicants: Browning - Inventors: Ryan D. Cook; Richard F. Korth - Web page: https://patentgrep.com/patent/US10371475B2 ## CPC - F41A 17/36: locking the gun {automatically} in a safety condition when the magazine is empty or removed {(F41A17/44 takes precedence)} - F41A 9/26: using a revolving drum magazine - F41A 9/73: Drum magazines - F41A 19/15: Modular firing mechanism units - F41A: FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE ## Abstract A number of embodiments of a firearm are disclosed where the firearm includes a magazine configured to hold the bolt in an open position when the magazine is empty. In one embodiment, the firearm includes a bolt stop mechanism that moves between a first position where it allows the bolt to cycle between an open position and a closed position and a second position where it holds the bolt in the open position. The magazine is configured to actuate the bolt stop mechanism to the first position when the magazine is empty. ## Claims ### Claim 1 A rotary magazine comprising: a housing having an interior cavity and a feed opening; a rotor rotatably positioned in the interior cavity of the housing, the rotor being configured to feed cartridges through the feed opening; a tab movable between a retracted position and an extended position relative to the housing by rotation of the rotor; wherein the tab is configured to operatively engage a pivot member of a bolt stop mechanism to maintain a bolt of a firearm in an open position by moving the tab into the extended position. ### Claim 2 (depends on 1) The rotary magazine of claim 1, wherein the tab is configured to pivot the pivot member relative to the firearm. ### Claim 3 (depends on 1) The rotary magazine of claim 1, wherein the tab extends through an opening in the housing adjacent to a corner of the housing. ### Claim 4 (depends on 1) The rotary magazine of claim 1, wherein the tab is positioned in the extended position when the magazine is empty. ### Claim 5 (depends on 1) The rotary magazine of claim 1, wherein the rotor comprises a protrusion configured to move the tab from the retracted position to the extended position. ### Claim 6 (depends on 5) The rotary magazine of claim 5, wherein the protrusion is configured to move the tab when a last cartridge exits the rotary magazine. ### Claim 7 A rotary magazine for a firearm, the firearm including a pivot member operatively coupled to a bolt stop mechanism, the bolt stop mechanism being configured to hold a bolt of the firearm in an open position, the rotary magazine comprising: a housing having an interior cavity and a feed opening; a rotor rotatably positioned in the interior cavity of the housing, the rotor being configured to feed cartridges through the feed opening; a tab movable between a retracted position and an extended position relative to the housing by rotation of the rotor, the tab being configured to contact and rotate the pivot member of the firearm as the tab moves to the extended position; wherein rotation of the pivot member actuates the bolt stop mechanism to hold the bolt of the firearm in an open position. ### Claim 8 (depends on 7) The rotary magazine of claim 7, wherein the tab in the retracted position is completely retained within the housing. ### Claim 9 (depends on 7) The rotary magazine of claim 7, wherein the bolt stop mechanism continues to hold the bolt of the firearm in an open position when the rotary magazine is removed from the firearm. ### Claim 10 (depends on 7) The rotary magazine of claim 7, wherein the bolt stop mechanism contacts a portion of the bolt to hold the bolt of the firearm in an open position. ### Claim 11 (depends on 7) The rotary magazine of claim 7, wherein the pivot member and bolt stop mechanism are pivotally connected. ### Claim 12 (depends on 7) The rotary magazine of claim 7, wherein the tab is biased to move to the extended position when the rotary magazine is empty. ### Claim 13 (depends on 7) The rotary magazine of claim 7, wherein the tab comprises a tab protrusion, the rotor being configured to move the tab from the retracted position to the extended position by engaging the tab protrusion. ### Claim 14 A rotary magazine comprising: a housing having an interior cavity and a feed opening; a rotor having a protrusion, the rotor rotatably positioned in the interior cavity of the housing, the rotor being configured to feed cartridges through the feed opening; a tab having a notch, wherein rotation of the rotor causes the protrusion to push on the notch of the tab to move the tab from a retracted position to an extended position relative to the housing; wherein the tab is configured to completely reside within the housing in the retracted position. ### Claim 15 (depends on 14) The rotary magazine of claim 14, wherein the tab remains in the retracted position when there is at least one cartridge in the rotary magazine. ### Claim 16 (depends on 14) The rotary magazine of claim 14, wherein the protrusion contacts the notch at an approximate midpoint of the tab.