MGSV got much better once I figured out how CQC and holdups worked. CQC lets you drop someone without using ammo. You can move them while they’re unconscious, and then wake them up with a kick. Once they’re awake, you can hold them up while they’re on the ground. If they’re held up, they’ll stay on the ground permanently (unless another guard finds them and gets them up). So you can capture an entire base without using ammo, simply by finding a quiet corner to stash your guards in; You don’t need to worry about them waking up from a knockout, cuz the holdup keeps them down.