I measured the gap on the 18500, it is roughly .050, so a thinner oring under the battery would not work nor would black tape, keep in mind the oring under the battery serves two functions, one, to insulate and two, to act as a spring keeping constant pressure on the battery to top post connection which is even more critical now that you have the kick in there due the extra two electrical connections. Trust me fellow ecfer's, the only truly effective solution is a shorter kick, different cap or longer body, with the cap being the most cost effective at this point. To hold you over, the Oring placed on the top cap is effortless and effective.