Vulcan shooting down 110 fps

Put the Vulcan over the Crony this weekend the velocity was a 110 fps slower then the first time I Crony’d it which was verified by Talon Tunes with 18.1 JSB. Spoke with Greg first who gave me some idea’s I did everything but check the barrel placement which Evgeny asked me to check today. And it’s not that, the grub screw is lined up with the indent in the barrel. I also did a physical inspection of the Breech O’ring which is in place and then I checked the transfer port with a kleenx for a possible leak of that O’ring. All looks good. Called Talon Tunes left message no call back. Any idea’s please leave me some feed back. I messed with the HST nothing there either.