Can you use a LR atty on a 510 5volt PT?
See the revised chart* below:
At true 5 volts there isn't any 510 LR atty that doesn't put you in the 'red' area. Which means that you'll easily burn out that atomizer. In fact, the regular 510 atomizer puts you in the caution/yellow area. While you can use the 510 atty in that area, you have to keep it extremely wet, no really long draws and you're still more likely to burn it out. The 'safe area' - the green area - shows that you need an atomizer or cartomizer that is around 3 ohms or above to run safely at 5 volts.
*original chart by Ralph T.