I came across these very detailed cannons in different scales on 4h model.com. these can be purchased via Taobao, see link below:
m.intl.taobao.com/detail/detail.html?spm=a230r.1.14.40.7e237f32NY42tY&id=520799477219&ns=1&abbucket=6#
m.intl.taobao.com/detail/detail.html?spm=a230r.1.14.40.7e237f32NY42tY&id=520799477219&ns=1&abbucket=6#