I do have pictures of a few guns that I took in CFB Borden in the past years. I have a few of a 37mm PaK 36, 50mm PaK 38, 75mm PaK 40, 75mm PaK 97/38, 105mm leFH18, 150mm sFH18, 76.2mm PaK 36(r).
I'm sure that I also have a few of a Puppchen and a 28mm Anti-Tank kicking round somewhere...
You just want the firing mechanism details?