Dead Eye is one of the best abilities in Red Dead Redemption 2 as it allows you to slow down time and pick off your enemies one by one. You can use Dead Eye all the time though, because if you do, you will drain your Dead Eye Core and Dead Eye Bar.
Each time you use Dead Eye in Red Dead Redemption 2 you will drain the Dead Eye Bar and ultimately the Dead Eye Core. To recover the Dead Eye ability you are going to need to eat foods and drink potions that recover the Dead Eye core and Dead Eye Bar.
Elixirs and potions can be purchased at the General Store in numerous towns, but they can also be made by crafting if you’ve found the right recipes. These items can be crafted at campfire, as well as mobile campfires or any other campfire that you come across. Crafting can also be done when resting. Some potions and elixirs will fortify your Dead Eye bar or Dead Eye Core. These items will make the Dead Eye core or bar turn yellow and during that time it cannot be drained.
Food can also be purchased at the General Store but you can also cook food at a campfire. You can cook animal meat that you have killed while hunting to replenish stamina core.