Carlson's Choke Tubes Choke Tube Snap Caps 20 Gauge Brass Wool 189111. Treat the wool chamber mop with your favorite gun oil to prevent rusty chambers during storage. NOTE: leaving guns cocked during storage is hard on springs and is dangerous. These will help keep your shotgun in good condition. 2 per pack. Specifications for Carlson's Choke Tubes Brass Wool Shotgun Snap Caps: Manufacturer: Carlson's Choke Tubes Fabric/Material: Brass/Wool Quantity: 6 Color: Red Package Contents: Carlson's Choke Tubes Brass Wool Shotgun Snap Caps Carlson's Choke Tubes 189111: Choke Tube Snap Caps 20 Gauge Brass Wool