Simply thread a Hornady Lock-N-Load Conversion Kit into your RCBS Rock Chucker or other reloading press using a 1¼"-12 thread, and you're ready to start using the Lock-N-Load System. It's the easiest way to get the most out of your reloading press. These bushings let you take advantage of Hornady's Lock-N-Load technology even if you own a competitors reloading press.