I am not here to debate if you need these and not, I've never had a problem with my chuck with any batteries I've used in it... but I thought it would be an easy thing to come up with and couldn't hurt.

So, I found some good stuff for a tube liner. I stole it from the kitchen. It's a mostly clear piece of plastic that has a cross hatch texture on one side and is smooth on the other side. It's about 9" x 9" square. I'm told (by it's previous owner and soon to be owner of some new ones) that it was intended to be put over your food in the microwave to keep splatter down. If it's 'microwave & dishwasher safe' it must be 'mod safe' too, right?

Anyway you can cut 12 tube liners out of one of these. Don't cut it so it fits tight. You wanna leave a gap so that after it's rolled it does not go all the way around the inside of the tube (I left about 3/16" to 1/4" gap). The dimensions are about 2.5" x 2.25". This stuff is also of a thickness that leaves the batteries a little loose. This is good for a couple reasons but one is that it allows the batts to still go in and out very easy. While I cut these for my Chuck I'd bet they would've fit my (recently departed) Maxi RoughStack or an extended Bolt or pretty much any tube designed for an 18650 that you're stuffing a pair of 16340s into. [reference the appropriate warnings and disclaimers elsewhere and pretend they were here]
A little trimming MIGHT be required for some of those mods but I don't have any here to try it in. The plastic will cut with good sharp pair of scissors (no, not the little rounded tip ones in the kiddie stuff).

Oh yea, I put mine in with the slick side to the copper pipe as it makes it slightly easier to pull out should you decide to do some 3.7v vaping with the 18650 battery.

Anyway, if this is too much of a pain to go find the material and cut then I can mail you a FREE one (I have 10 more cut for a Chuck) if you send me a postage paid, pre-addressed envelope I'll put one in your envelope and drop it back in the mail to you. First come, first serve. PM me, I'll mark one as gone, send u my mailing address and then mail me your envelope. PM me with the subject: TUBE LINER.

When these are gone I doubt I'll go get the stuff and cut more but ya never know.


Skip

PS: You can buy an nice machined derlin flashlight battery tube for $14 HERE. Frankly, besides not liking the price tag I don't like that they didn't cut a channel lengthwise in it. I'm told batts swell before they vent.

PPS: I am NOT dishin' the Chuck. Frankly even if you could get a batt to vent I have my doubts about it being able to do anything to the Chuck as sturdy as it's built. Preventing the situation is always better though and... Hey, you can tell people u have a custom safety option on yours.