Another helpful tip from the Brain Exploder as he covers the topic of stopping the inner barrel from moving inside the hop-up unit... "If you've ever noticed your barrel moving out of place during the install or use period this might be the fix for you. Hopup innovation is slow and almost nonexistent so we are forced to innovate on the diy front. With this average difficulty mod you can ensure that the install you made outside your gun stays that way as you install and use your airsoft replica. Give it a try and let me know how it turns out.

Be sure to use a throw away barrel when making the original hole."