You'll just have to examine the pin on your FS when you get it and make sure it doesn't give any or act spring loaded. The pin must protrude well below the threads of the 510 connector. Most RDA's seem to have solid pins that stick out plenty far from the threads but still important to check each and every atomizer. (It's the tanks causing problems with flush pins or close to flush that compress just enough to cause a short.)
A hybrid mech mod heats up damn fast when the battery shorts. Too hot to hold in about 4 seconds. Don't ask me how I know this.