some older footage from 2002, JMU RB, Curtis Keaton, uses the plyo hang clean technique to launch 405 and then 420. This is not your traditional USAWL technique. Emphasis is on activation of the stretch shortening cycle through both an explosive eccentric prestretch and successive explosive concentric action. The optimal vertical impulse position must be utilized by placing your knees forward under the bar and explosively extending your hips and knees with your back unright. You must be as explosive going under the bar as you are getting the bar up. Accelerate the mass upward, quickly decelerate the mass as you go under it to catch and then use your strength to stand it up.