[mcguyver]

The bucking is the little cylinder. If you take out the barrel and look down it from the nozzle end, you should be able to see the bucking move the sleeve as you turn it up and down. If it is not moving fully off to fully on, remove your barrel and check everything in the chamber again. When I install a new barrel or hop sleeve, I put a little silicone oil around the outside to help it slide into the chamber easier and let you avoid making any jerky movements during installation. This lets the bucking stay in its place and not cause you any grief.