Does the inner tube come out?
We can just add some kapton tape to the inner tube to solve all possible problems?
We don’t even know there is a problem. I am sorry I got everyone worried about something that might not even be.
^ Yes tape can fix anything 
One layer of kapton tape was all I could fit. Any more than that and it won’t fit into the outer tube any more.
I don’t know if the tail parts will be glued or not, so I don’t know how easy it’ll be to open. Regardless, that doesn’t seem to be an issue as much as making sure the driver fits into the proper place. Proto1 and proto2 were totally fine in that regard, I never saw a proto3, and proto4 didn’t have quite a large enough space cleared out for the driver.
Detailed info has been sent, but everyone there is on holiday for a while so there is no response yet.
Cool. I’m guessing there is a retaining lip at the switch end of the tube?
Yes the driver cavity being correctly machined is quite an important aspect of this build.
What voltage level did you use for the 50%? 3.6V?
I discharged 1400mAh out of a 30Q whose capacity I first measured at 2800mAh. The resting voltage was at about 3.75V.
Yep, you can see the lip in this drawing, meaning it has to slide out from the tail cap end.
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Great review, thanks! Very detailed post with all the tech stuff we need 
Has anybody modded this light into a quad? Would standard quad parts fit into the head?
The FW3A isn’t even in production, so no quad mod.
Right. It would be a build from scratch at this point, not a mod.
Yeah 
Show off.
I’m allowed bragging rights 
I agree.
Could anyone who has a prototype measure the ID of the head to see whether the 4x up Carclo fit?
I have enough triples but would mod this into a 4x Nichia with Carclo.
Thanks.
No chance. Carclo’s 4-up optics are 24mm, while the triples are 20mm and the triple is quite a snug fit.
I measured the ID at 20.4mm.
Did anyone also send summary feedback to the manufacturer regarding the issue of the length being slightly too short?
I don’t think there was ever an issue of the battery tube being too short. There were however instances of the driver not sitting down into the driver cavity all the way which thereby made it seem like the battery tube was too short. Maybe that is what you’re referring to. And yes, this issue has been relayed back to the manufacturer.
I must have missed this reviewer’s statement of why the batteries didn’t fit. He stated that button top batteries wouldn’t work, and that tightening the end cap dented them. I assumed this mean the tube needed to be lengthened, but it sounds like recessing the driver more is the real solution. Anyway, glad that it is being addressed. It would make no sense at all to produce this light in a configuration that would not accept both types of batteries.