Vincent

A 2 Litre bottle with a JetCat clunk will not introduce air-we run this without any UAT or hopper and have 100% success. The fixed centre tubes in my hopper will allow a third air in the hopper and I doubt I'll see more than a 1/8th when I land.
I won't have a priming issue as the hopper stays full and when I disconect the 2 litre bottle the quick release seals on the hopper.
The reason a "Pop" bottle works so well is the clunk (and flexible clunk tubing) My Harpoon drains completely dry including flips and 3-D stuff. I run a BVM UAT for added capacity and it never has more than an 1/8" of air!

Dave Wilshere