Okay, try removing ALL THREE of the deck gun mods you've added and let me know what happens afterwards.
I can tell you this definitively though... it is a problem related specifically to your installation, as most everybody else's deck guns work normally.
It could come down to a full uninstall-reinstall if we can't figure it out here.
Just a note though, just because JSGME doesn't tell you that nay files are overlapping... doesn't mean that the files you add... are safe. All JSGME will let you know is if files are overlapping. Bad mod data is not prevented by JSGME.
(I hope I explained that clearly... re-reading it made me eyes cross a bit.
)