Since it's not clearly defined what 80x tougher means, I'll make the easy comparison, one based on energy of the projectile. This is very fuzzy, so it doesn't really matter if we're talking about muzzle energy or impact energy to get a rough estimate.
I would also estimate, that anything able to cut, such as arrows or crossbow bolts with hard enough cutting edges, would likely be lethal at much lesser energy than 80x. The ideal shape of the arrow head would likely be different than normal hunting arrows of this type, probably much narrower to allow deeper penetration and better chance of reaching arteries. The exact effects of different projectiles would be impossible to know without experimenting with real ballistic material matching this 80x tougher human tissue and internal organs.
But let's get to the beef of this. 100 to 200 Joules can be taken as the energy range of non-lethal projectiles, based on random internet searching.
If we multiply that by 80, we get range of 8000 to 16000 Joules for non-lethal but debilitating projectiles. So let's say below that will not really slow these tough guys much, while above that can easily be lethal.
Now if we look at this page, the highest power gun listed there is rifle using 7.62 × 51 mm ammunition, with 3799 Joules of muzzle energy, Well below the non-lethal range.
Based on this simple energy comparison, it would not impart enough energy to be able to seriously injure your 80x more durable person. It would hurt like hell, and cause serious bruising and bleeding, but it would not cause a debilitating injury, unless it hit something like an eye, throat or a temple.
So, what would be enough? .50 BMG aka 12.7×99mm NATO machine gun round has energies in the range of about 18000 to 20000 Joules. So that would likely be at least debilitating with a single hit, and certainly lethal with repeated hits.
It is probably relevant and notable, that there are sniper rifles, which use this bullet (example). Those would be effective, though only at quite short range.