by Lancer » Tue Nov 20, 2012 4:58 pm
Try switching to the stock barrel and see if that fixes it. The 650mm is about as big as you can get, and if you don't have the proper cylinder for it, your shots will come out far slower than they ought to.
Also, that long of a barrel will exacerbate any compression issues you might have, as you really need nearly perfect compression to maintain enough pressure to push a BB out of a barrel that long.
And as a side note, the addition of sorbothane will likely decrease your cylinder volume and therefor decrease the total amount of air you can put behind a BB, which given your current problem (assuming the barrel is prohibitively long) will only make your condition worse.