Misc. tips using the triple XPG V3 in a Surefire 918FA.
1) I had to make a ring out of 12ga copper wire to put between the lamp assembly and the "flashlight" body before it would work (trick seen elsewhere on CPF but I don't have a source).
2) The "shock" head on the 918FA doesn't put enough pressure on the lamp assembly for it to make positive contact after sitting over night. I did purchase the spacer, and that would probably work, but it crushes the shock material to the point I suspect it would probably deform over time.
Short term I stuck a G2 head on there and that works fine, so I've ordered a Z44 to replace the shock head.
3) The 918FA is a 3x123a configuration. Since it holds two cells in the "tube", or body of the light, and one cell in the fore-arm, it isn't really practical to go to a bored configuration. Since it doesn't look like I can run 3x123a, I decided I would go with 2x17670. Of course to get there I need to extend, so I ordered an A19. I guess I could have replaced the existing 2x123a length body with a 9P body and have one-piece, but the A19 is a fair amount cheaper.
Later, I found Dereelight has an extention tube that might work and is cheaper, but I had already ordered the A19 and I don't know for sure if the Dereelight part would mate correctly. It is EXT500 and $10. Shipping is like $2, so it is a good deal. I actually ordered a full CL1H V4 host with tubes, so I'll see if it fits when it gets here.
4) I had to order some protected 17670 cells because of #3.
So this was a bit more painful (and more expensive!) that I had anticipated, but now the 918FA is as bright as it deserves. Quite an upgrade from 200lm and 19 mins. runtime on 3 cells!
Edit: One remaining outstanding item is my concern about recoil using the 2x17670s. Surefire actually sells a "battery pack" of 3x123a cells shrink wrapped together with some sort washer between the cells to prevent crushing. I figure I might need to do something like that to prevent the buttons (and possibly the protection circuits) from being crushed. If anyone has ideas about this, I'm all ears. Thanks.