How do you load up the slug ammo for the shotguns

[Jonboy]

?

[Andy Mil]

Edit slot --> select ammo and there will be Slug
highly suggest to avoid it unless you doing for research. It take 3 shot to kill sus
Stun is random
knockout is unlikely

[Graywolf364]

If you mean in mission, it's the same as the other ammo types switchs. You press 1 an additional time and it will load the other ammo type. You can also set a dedicated key for ammo switching I set mine as H just because that was the first key I came across.

Just note that ammo switching for shotguns is a bit counterintuitive if you're not familiar with how shotguns work. The new ammo will only be loaded if there is empty space in the tube for it. Shotguns start unrealistically at full capacity and there is no way to clear the chamber beyond firing.

As an in-game explanation, if you start your mission with your shotgun fully loaded with buckshot and you want to do a select slug, you have to fire the shotgun once. Press the change ammo/primary weapon equip key. A single slug will be loaded into the tube. Then you to fire again this, shot will be buckshot. Your shot after that will be a slug.