The Micro was conceived with sportier weight barrels in mind. However, this brake has gained popularity in the “AR” market as it is both lighter and more effective than most every brake in the 3-gun world. Also easier to install. The Gen 2 has a nut that is a separate piece. This allows our customers to install the brake themselves at home. Installations take about 30 seconds and have no hideous crush washers or peel washers to deal with. Additionally, competitive shooters can easily remove this brake for cleaning or simply to move if from barrel to barrel. Competitors can burn through 6 barrels or more in a season at times. This brake is meant for smaller barrels from AR-15's to hunting rifles. We recommend a barrel diameter of .600-.750 inches for this brake. APA Gen II Micro Bastard .22 9/16x24 Brake