If you're like me and like to play zombies with a controller then you'll understand the absolute beauty of what we know as Target Assist/Auto-aim. I found this feature missing in a lot of custom weapons on ZM maps and even my own ports.
It's a simple setting in the weapon asset (credit to Hitman who found the settings in Kuda's weapon):
The Auto Aim Range seems to handle the Auto-aim when you ADS so I set that to the same as the assist range, though you might want to increase it. Simply type "auto aim range" into the search to find it.