Kleenbore Military Style Brushes .223 and 5.56mm Bore Brush, #8-36 Threaded Coupling - All KleenBore military style brushes are designed specially for M-16, AR-15, AK-47 and similar rifles. The brushes are available in .22/.223/5.56 mm and .30/7.62mm, and feature core wire looped through a brass coupling that is threaded at #8-36. The chamber brush has two diameters; the first stage of phosphor bronze cleans the chamber area, while the second stage of stainless steel cleans the bolt-lock area. And, bore brushes are made of phosphor bronze with a brass wire core for a longer life for rigorous cleaning