Nice rig, with the step down adapter...can you remove the bottle without taking the barrel off?
Here is my QB bottle gun. I started with a .177 AR2078 and a QB79 as a donor for the tank block and tube. Pretty much just cut the notched end off the valve and removed piercing pin to gain a little extra space. De-burred everything and replaced all o-rings, opened up the bolt probe. Did a 1 o-ring bstaley mod to quiet down the hammer. Ninja tank regulated at 1100psi.Also used the tank drop adapter as I may build a full shroud at some point. Currently shooting 775fps with Air Arms 10.3 Diablo field heavy. Very accurate and very quiet.