Dynavap stainless steel alloy types (taken from George himself on a
reddit AMA )
"All parts of the M are 316L. The cap is 304."
Thermal expansion coefficents for steel vs titanium taken from
here.
Material / Thermal Expansion Coefficent value
Ti / 4.8 TE
SS316 / 8.8 TE
SS304 / 9.6 TE
I believe that titanium's low coefficient value means it expands less than stainless steel while heated up.
I feel frustrated about the tip not fitting right, but part of the issue is my own o-rings - so I can't blame everything on high tolerance. Like you said, it's a easily mitigated issue; that's a decent silver lining. Thanks for the suggestions everyone.
On the positive side of things, This is my stop-gap solution until I figure out what to do next. I actually really like the experience of combining the BB6 and the helix stem like this. Like, very thoroughly enjoy it. The helix is to the BB6 what the M7 adjustable mouthpiece is to the M; the essential extension I never knew it needed which just completes the setup.
The BB6 stem adds that extra air path and a regular carb for fine tuning the airflow. The helix bubble is just far enough away from my eyes to watch the vapor combine with air and form a vortex tornado-type swirl through the piece - it's fun to watch! A little top heavy on the helix side, but it feels real nice to hold. Great to operate. Now thats a magic wand!
Being able to see inside the bubble also helps keep track of how dense your vapor is. I feel that I can get more use out of the half-bowl by making sure to back off the heat when the vapor becomes just visible. If you start hitting before the vapor is fully visible, then cut the heat and hit it long enough for the vapor to go away - this makes for a perfectly satisfying terp-chaser hit.
Doing this over and over can help squeeze many extra cycles out of a half-bowl. I think that adding a low-temperature cap and titanium tip would make this setup an efficiency beast.
Truthfully, though, I have a love for my sole SS M+ tip and trusty captive cap - they've always worked faithfully for me and I know how to work them to get terpy efficient hits all the same. In my experience, intelligent energy application with these two is far more important than any material differences.
To conclude, the glass absolutely does help cool the vapor. The way the air is introduced by the small sharp angled air hole helps mix it really well and adds some precious extra time swirling in the air path before hitting the lungs. It feels nice to hold and the vortex adds nice visual flair as well as a great way to meter the vapor density.