The below concerning battery type & length is from the OP (post #1) of the main thread, FW3A, a TLF/BLF EDC flashlight .
- Runs on a single 18650 battery.
- 92.5 × 25.5 mm: Unusually small for an 18650 light —
about the size of a SK-68 (1xAA).
- Battery size: 18mm x 65mm (66mm maximum). Protected cells won’t fit.
So maybe another thing missing is that it appears there is no need to change anything concerning “tube(s) length”. It was stated long ago that the ’maxium battery length’ was 66 mm. And that ‘protected cells’ would not fit.
Simple as that, it appears to me.