High-grade Explosives Deal
Head to the marked location in the bayou. You can circle behind the train cars and take out the perimeter enemies one by one there. Once you think the number has been reduced, you can go ahead and engage the remaining hostiles in a firefight. Use your intel view to identify the hostiles from the civilians just joining the shooting party. Once cleared, you can destroy the remaining weapon & ammo crates if you haven’t done so yet. Don’t forget to loot the considerable amount of cash as well.
Military-grade Weapons Deal
Head deeper in the bayou to find this weapons deal. There’s another firing range but not all of them are targets. You can take out the guards from behind the train car then go loud once you took out enough of them. It’s better to go loud by throwing a grenade or molotov so at least you can take out at least a couple of enemies before they react.