Hi Epervier,
I dont know if this is a solution for the gunner problem but some time ago i have a problem with a mod i have downloaded.
The mod where only Msh. files and textures.
The problem i had was,when i fire up a rocket only one rocket flys and directly strait down into the ground.
and when i switch after that to the flyby-mode the plane goes crazy fast.
I have found out that there was a missing textur or a damaged msh file in the 3do/arms/Weaponxxx(dont remember the name) folder.
When i deleted this folder i can shoot my rockets as normal.
The same problem i have long time ago with a plane, when it crashed the pilot flying in a fireball over the map.
The solution was a missing texture or msh. file of the pilot when i remember.
What you can check out is that you add other Mguns to the class files,i think the mguns you have added to the classfiles maybe have no msh. or missing texture file
or is not in the 409.
All the best and thanks for your 409 work! Germy66