Have any SC52 owners noticed the O-ring is too small and doesn’t give a good seal?
I tried a 2x14 O-ring, and that was slightly better, but still causes no resistance when screwing the tailcap on.
Today i tried a 2.5x14 O-ring. This is slightly too chunky and causes a very tight fit of the tailcap, but at least i know its sealed well 
No, SC52 cool white.
Nope, i get that little release pop when i unscrew past the O ring. Maybe you haven’t got enough grease on the threads and around the O ring giving a proper seal.
SC52 CW version.
I tried putting lots of grease on the o’ring to see if screwing the tailcap on would mush it in and then I’d know if it was making contact, but the grease was in little blobs, just like when I applied it.
Changing the o’ring to a slightly chunkier 2x14 improved things a little, but it only just made the grease mush, and there was still no resistance.
I then put a chunky 2.5x14 o’ring on and this is nearly too fat, but I’d rather have it a little tight like this and get a proper seal.
the o-ring might have production tolerances.
great that you could fix it with a thicker o-ring.
as i had found out, if an o-ring groove is properly designed with tight tolerances (e.g. see Xeno E03 or Nitcore Tiny Monsters), then there is only 1 single o-ring size which fits perfectly for the purpose. this is especially true since commercial o-rings have standardized sizes, in steps.
Yes, the Spark SG5 has a perfect fitting O’ring in comparison. I’d still like to get hold of some other size orings to try and see if I can get it perfect.
If you find a perfect fit I’d be interested to hear it, I’ve never had a water problem, I’ve also never submerged it, but I have wondered about the amount of dirt that gets in the thread lube past the O-ring, I never lock out the tail so it all gets in there right past it.
I’ll post here when I’ve got some different o-rings to try.
I went threw my spare o-ring container and found one that was the exact size but just a little thicker and it seems to seal much better, you can really feel it being compressed when you screw the tail cap on. I broke my digi caliper last week trying to clean it so its out for warranty service and I have no way to measure, not very helpfull I know.
Sounds promising. Let me know if you manage to measure it.
This could be a bad idea, but Harbor Freight sells assortments of orings in both “I think” standard and metric sizes cheap. Maybe a standard vs metric might have a better fit?
Yeah good idea, worth having a selection to try.