I see what you've built and I think it's been a great build. A couple questions if you wouldn't mind satisfying my curiosity.
Why did you decide to add the bay to the end of the nose cone rather than lopping off the end of the cone and building inside?
I see that there is air space shared between the av-bay and nose cone. I assume this is where you will have your ambient pressure readings for the bay via a vent hole in the nose cone. Will you also use this passage for your arming/disarming wires/switch?
The o-ring seal. Is this rolled over the tube just resting against the cone? If so, you may think of making a seal by putting some RTV on the end of the tube. When it is still soft but not tacky, push the tube against the nose cone with grease/Vaseline/wax (just a release agent of some sort) applied to nose cone. Once RTV is set up, you have a removable connection with an official gas seal. Either way, be sure to ground test and hopefully you won't get charge pressure leaking into the av-bay.
Thanks
Mark