Im not really sure what point you are trying to make here. As I said, we construct belts with regards to two factors. A) Historical / Sourced based consideration as to what shells were available for the gun / vehicle and B) Balance considerations. Even if something is a prototype, its possible to find details on its guns, possible ammunition and from that construct belts from the sources and materials that are avalable.
The question asked to me was if a crew statement was sufficient to report something. As far as our reporting standards go, no, as explained crew statements are not sufficient by themselves. Claims and statements are made all the time about vehicles from crew that differ from well established sources, so sadly, we cant accept them.