# US 8,739,450 B2 · Barrel extension > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,450 B2 - Document ID: US8739450B2 - Status: Granted - Kind: B2 - Application number: 13/739,404 - Filed: 2013-01-11 - Published: 2014-03-20 - Granted: 2014-06-03 - Earliest claimed: 2012-01-11 - Assignees: E.R. Shaw, Inc. - Applicants: E.R. Shaw, Inc. - Inventors: Roy Piontek - Web page: https://patentgrep.com/patent/US8739450B2 ## CPC - F41A 21/10: Insert barrels, i.e. barrels for firing reduced calibre ammunition and being mounted within the normal barrels - F41A 11/02: Modular concepts, e.g. weapon-family concepts - F41A 21/32: Muzzle attachments or glands (F41A21/26, F41A21/30, F41A21/46 take precedence {; for projectile velocity measurements G01P3/665, G01P3/685}) - Y10T 29/49826: Assembling or joining - F41A: FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The present invention relates to barrel extensions for firearms that have been converted to fire different, most likely lower, caliber ammunition than the firearms were originally designed to accommodate. The present invention in several embodiments is a barrel extension designed to supplement or replace the barrels and/or barrel extensions of firearms that have a sub-caliber conversion installed. Several embodiments of the present invention are configured to be installed on AR15 family rifles with a .22LR ammunition conversion to allow for accurate shooting of the .22LR ammunition through the barrel extension. ## Claims ### Claim 1 A barrel extension device for use with a firearm for use in changing a caliber of ammunition of a firearm from a first caliber ammunition to a second caliber ammunition comprising: a barrel extension comprising: a body having a first end and a second end, and a cylindrical sidewall extending between the first end and the second end, said cylindrical sidewall defining a cavity, wherein at least a portion of the cylindrical sidewall is threaded internally and configured for attachment to a barrel, wherein the first end of the body is configured to cooperate with a caliber conversion device to enable firing of a firearm when said caliber conversion device is installed in said firearm so that the firearm can shoot the second caliber ammunition, and wherein the first end of the body is shaped not to cooperate with the bolt in the bolt carrier assembly for the first caliber ammunition to the barrel extension preventing firing of the first caliber ammunition from said firearm when said bolt carrier is installed. ### Claim 2 (depends on 1) The barrel extension device according to claim 1, wherein the first end of the body comprises no indentations required for receiving the bolt of said bolt carrier assembly. ### Claim 3 (depends on 1) The barrel extension device according to claim 1, wherein the cavity is configured to receive an exterior profile of a caliber conversion device. ### Claim 4 (depends on 1) The barrel extension device according to claim 1, wherein the barrel extension comprises flat portions on an exterior surface of the body of the barrel extension. ### Claim 5 (depends on 1) The barrel extension device according to claim 1, wherein the barrel extension and a barrel are secured to each other. ### Claim 6 (depends on 1) The barrel extension device according to claim 1, wherein a barrel configured to shoot .22LR ammunition is secured to the barrel extension. ### Claim 7 A kit of parts for installing a barrel extension device in a firearm for use in changing a caliber of ammunition of the firearm from a first caliber ammunition to a second caliber ammunition, the kit comprising: a barrel extension, and a barrel, wherein the barrel extension comprises: a body with a first end and a second end, and a cylindrical sidewall extending between the first end and the second end, said cylindrical sidewall defining a cavity, wherein at least a portion of the cylindrical sidewall is threaded internally and configured for attachment to a barrel, and wherein the first end of the body is configured to cooperate with a caliber conversion device to enable firing of a firearm when said caliber conversion device is installed in said firearm so that the firearm can shoot the second caliber ammunition, and wherein the first end of the body is shaped not to cooperate with the bolt in the bolt carrier assembly for the first caliber ammunition to the barrel extension preventing firing of the first caliber ammunition from said firearm when said bolt carrier is installed. ### Claim 8 (depends on 7) The kit of parts for installing a barrel extension in a firearm according to claim 7, wherein the first end of the body comprises no indentations required for receiving the bolt of said bolt carrier assembly. ### Claim 9 (depends on 7) The kit of parts for installing a barrel extension in a firearm according to claim 7, wherein the cavity is configured to receive an exterior profile of a caliber conversion device. ### Claim 10 (depends on 7) The kit of parts for installing a barrel extension in a firearm according to claim 7, wherein the barrel extension comprises flat portions on an exterior surface of the body of the barrel extension. ### Claim 11 (depends on 7) The kit of parts for installing a barrel extension in a firearm according to claim 7, wherein the barrel extension and the barrel are secured to each other. ### Claim 12 (depends on 7) The kit of parts for installing a barrel extension in a firearm according to claim 7, wherein the barrel is configured to shoot .22LR ammunition, and is secured to the barrel extension. ### Claim 13 A method of installing a barrel extension device in a firearm for use in changing a caliber of ammunition of a firearm from a first caliber ammunition to a second caliber ammunition, the method comprising the steps of: providing a kit of parts for installing a barrel extension in a firearm, the kit comprising: a barrel extension, and a barrel, wherein the barrel extension comprises: a body with a first end and a second end, and a cylindrical sidewall extending between the first end and the second end, said cylindrical sidewall defining a cavity, wherein at least a portion of the cylindrical sidewall is threaded internally and configured for attachment to a barrel, wherein the first end of the body is configured to cooperate with a caliber conversion device to enable firing of a firearm when said caliber conversion device is installed in said firearm so that the firearm can shoot the second caliber ammunition, and wherein the first end of the body is shaped not to cooperate with the bolt in the bolt carrier assembly for the first caliber ammunition to the barrel extension preventing firing of the first caliber ammunition from said firearm when said bolt carrier is installed, attaching the barrel extension to the barrel, and attaching the barrel extension to the upper receiver of a firearm. ### Claim 14 (depends on 13) The method of installing a barrel extension in a firearm according to claim 13, wherein the first end of the body comprises no indentations required for receiving the bolt of said bolt carrier assembly. ### Claim 15 (depends on 13) The method of installing a barrel extension in a firearm according to claim 13, wherein the cavity is configured to receive an exterior profile of a caliber conversion device. ### Claim 16 (depends on 13) The method of installing a barrel extension in a firearm according to claim 13, wherein the barrel extension comprises flat portions on an exterior surface of the body of the barrel extension. ### Claim 17 (depends on 13) The method of installing a barrel extension in a firearm according to claim 13, wherein the barrel is configured to shoot .22LR ammunition.