I have 1 of the 3 evods that I have in rotation currently that will start to unscrew the atty head from the base when I remove the base. it so far has always stayed screwed in enough to not leave it in the evod and dont think it would be hard to remove by itself either, just saying.
the evod is a good atty to stay off the stinkies. I truly like the ones I have used. I have 5 more as backups and prolly 15 heads and 2 new bases as well