The home insurance give a better discount for 8d over 6d?
Old thread. There is no discount for 6d nails or staples.
6D nail, had to chime in 
How exactly can you determine the precise length of that nail to denote it as a 8d or 6d when you can only see one side of the nail? It could be under or over-driven…I would think if the roof deck was nailed correctly you shouldn’t see any nails. “Weakest for of attachment”=nail in the air…Nothing like putting a picture of a code violation in your report as verification of roof deck attachment.
This could be a tack nail or even one of the nails used to hold a tool or other type item on the roof…we did that all the time.