Can you clarify what a 80% fc pocket is? To be honest I think I know what you are talking about, but I want to make sure.
Generally I do not DuraCoat anything one cannot see once a firearm is assembled unless:
- the client specifically asks
- the inside finish needs to be redone because its in poor condition (or doesn't have one)
If I do DuraCoat internal items (and things with moving parts) I lay just enough thin coats to color it, but don't bother with a thicker protective coat due to tolerances. (The inside of an AR lower receiver would be a good example).
Allowed to cure properly, the thin coat will be fine, generally the internals of a firearm don't see a lot of traffic.