Actually the J118 (aka VX2 or Modern Vapor 902), will work on a 510 battery, but it takes a slight modification. But you do need a grinder to do the mod.
I used them this way for a few months, on a 5v mod with a 510 battery connector. I never had any problems. Then I finally got a hold of a few J118 dead batteries, so I've been using the right connectors since then, and the grinder is getting a rest.
Anyway, it takes less then 2 minutes at the most to get it right. I never used any special tools other then the grinder. I'd put a tight fitting mouth piece on the atty to be ground, (made it easier to hold), and would hold it in my hand for maximum control. There's very little danger because you're only using very light pressure on the grinder.
I've done this to about a dozen J118 atty's, and didn't have problems with any of them.
In the picture, you can see how a new J118 atty has a recessed positive contact.
The second atty is one of my older ones that was modified. You can see how the excess was ground off, so the positive contact is just about level with the rim of the negative contact (the screw part).
After the grinder, about 10 seconds of very light contact with the wire wheel to remove any burrs, and that's it, done. It will now work on a 510 connector. This really is very easy to do...... IF you have a grinder.
