Found These Two 5 Cent Coins Out Of Roll

The 1971 is simply very worn, perhaps with some old acid-damage (a "coca-cola coin"), or perhaps it's spent time in a rock polisher. The missing reeding confirms this. If by "flaw" you're referring to the stripe across the coin at the queen's eye-level, I suspect it's a lamination defect, normally invisible but that's been accentuated by the acid/wear damage.

I'm not sure what you're seeing wrong with the 1977?

High points of coin would initially be worn before outer spikes so pretty much the 5 would be alot flatter than this and coke wouldn't do this too a coin maybe a chemical, acid in coke generally wears out over night.