i am not 100% positive on it yet but i suspect that the walls are not equally thick of that tone whatever that is, its also thin enough that boolean might just fail there. if you use the intersect curve you can trim a hole right through it with one click. that should not happen… maybe rebuild that surface again maybe a tiny wee litte thicker.
ah and put those guns away, maybe replace it with a pool
OK, well it is out of whack and I cannot tell what the intention is - as far as I can see the centers of the shapes are not all falling on a line and the planes of the curves are not quite parallel. I’d get all that sorted out and build this thing cleanly. That said, Loft is behaving very strangely on some of the curves… digging into that.