I have noticed several times slow leaks often disappear by itself, over time. Here is a couple of examples: I once bought a bottle end cap, complete with gauge, when installing a regulator on a mk1 bobcat. First the gun had a slow leak, would probably loose 50% bottle pressure over night the first times I filled it. As I continued refilling the gun, the leak did seem to slowly disappear a couple of weeks later. Another case was when I installed a brand new, complete longer tube, on a wildcat. The first fills had a slow leak, and then it disappeared as I filled up the gun again several times. A third example is when I swapped out a bottle gauge, for a more precise one. Did first tighten the gauge up more, after the first slow leaks, but it was not completely gone yet. Thought to myself I would need a new seal, as I probably had tighten the gauge to much, and damaged it. Then after a couple of refills, it leaked less, and is now gone?
In all these cases the leak disappeared by itself, on 3 different guns. I do not know why, but I am happy they did. My pure guess is that the 0-rings gets a litle deformed by the high pressure, and slowly fills up the tine gaps leaking. Do not know if it made any difference, but in all these cases I refilled the guns, so they did not leak down to empty when stored away.
In all these cases the leak disappeared by itself, on 3 different guns. I do not know why, but I am happy they did. My pure guess is that the 0-rings gets a litle deformed by the high pressure, and slowly fills up the tine gaps leaking. Do not know if it made any difference, but in all these cases I refilled the guns, so they did not leak down to empty when stored away.
Slow leaks are sometimes hard to detect. Leak detector left over time on slow leaks will show a white fuzz that is hard to see some times. I always use diver silicone or another o ring lube on install of o rings. Not all o rings are made out of the same material and some have bad shelve life's. 