The manufacture does not provide this dimension. Since this is a "tactical" shotgun case you should be good as tactical cases will have more height .
Just bought this for the exact same KSG. It's a tight fit WITHOUT the Red Dot I have for it. I'm looking for something bigger, or at least WIDER/THICKER. The 29" length just makes it, but it's tough to zipper closed. Can't close it with the Red Dot mounted.