So, Is it a problem with the atty or the mod?The bottom 510 pin simply holds the bottom plate on and obviously makes the positive connection.
Shortest 510 pin of any Atty I own. Having minor ohm fluctuations when on my VS DNA200. Opened the VS up, no obvious way to adjust its 510 pin higher. No such problem on Pico or VTC Mini, those female 510's are more shallow in depth. I also have to SUPER TIGHTEN the kayfun's 510 pin, or the ohm drift is even higher. If you don't use TC mode, may not be an issue, so far it is for me.
OTH, I've become quite adept at making a coil last for months!