Definitely not Hincliffe. Why? Because I did the master for Steve Cox way back when
Making masters for metal casting had to be beefed up somewhat compared to masters for resin due to the casting process, so I was a bit heavier handed. That's my excuse anyway!
I have the MMS PaK43 in front of me and as you say, I see the small ammunition box behind the shield. Funnily enough, I don't recall spotting that when I built mine!
Hope this helps