If late war Arisakas were blowing up, I think we'd be hearing about it considering quite a few on these boards fire them on a regular basis as do members of all the other gun boards out there. There would be warnings in the magazines and books printed on the subject as there are with other rifles such as the early number Springfields. These rifles were brought back by the thousands and used by the thousands, many sporterized. There simply is no dramatic evidence out there that there is a hazard presented by these rifles that is not equal to or similar to all other old military types. On the contrary, they have found to be stronger than all other types. The fit and finish of the "last ditch" Arisakais not much different than that of the Mosin Nagants produced during the war and frankly, the quality of fit is much better.
As for stamped metal parts, the 03-A3 has stamped metal parts, the Enfields have stamped metal parts. Stamped metal parts are cheaper and easier to produce and were used by most combatants during the war. The Japanese went one step further and used wood buttplates to save metal. that doesn't mean they skimped on the barrel or receiver. That MUM represented their emperor who they considered to be God himself. It wasn't going to be stamped on a non-functional weapon and never was on any training rifle built as such.