Pro-Shot .223 and 5.56 Military Style Chamber Brush - 223CH Designed for competition shooters to withstand frequent use. Like our bore brushes, the chamber brush is also made to last with a brass core and bronze bristles. .223 Remington / 5.56mm diameter chamber brushes are specifically designed for military style rifles with a stainless steel skirt to aid in chamber cleaning. Standard American # 8-32 thread. This is a manufacturer's picture, so the item may not be exactly as it appears in the picture.