I have no idea how your code looks, but try to parent the gun to the camera, then you don' t have to care about it any longer. just load it with the camera as the parent, then translate it to the screen position you want it to be.
camera =createacamera()
gun=loadmesh("ak47.3ds",camera)
translateentity gun,.2,0,-.1,1 ; find values by trail'n'error
maybe you also need to scale the weapon.
camera =createacamera()
gun=loadmesh("ak47.3ds",camera)
translateentity gun,.2,0,-.1,1 ; find values by trail'n'error
maybe you also need to scale the weapon.