I loaded up a local game and chose my weapons and attachments.
In the beginning while driving with the truck I switched between primary & secondary weapons. I planted a bomb on the cache and got the detonator with the magazine attached to it. And then I tried every single item in my inventory & checked for the magazine (might missed it on some items).

Took a few screenshots & played till the end, but nearing the end I went on the vehicle w/ mounted mg and there was another mg above me. So I'm guessing it might be something to do with world model and client side models (I'm probably wrong here)

I have also noticed a bug with smokes.
While moving inside the smoke, it flickers between light & dark smoke. (I've had this issue on very high and low, haven't tried on other settings)