Okay guys I took my Vulcan all apart and cleaned it really good and after reassembling it would not group.and every so often would have a pellet clip mod and really go wild . I tried opening the holes up in my moderator a little bit but still the same problem. So then I remove the shroud and looked everything over and couldn't find nothing wrong. Then when I reassembled I realize what I had done wrong the first time. When I assembled it I had slid the Shroud all the way down against the receiver block then tightened up the end cap. That was my mistake. Make sure you leave a small gap between the Shroud and the block. After doing this my groups are back to 1 hole at 35yds. Just thought I'd share .
