Hi,
Without being 100% sure, I'm definitely with Ordman that it makes no logical sense to crush from the mouth down (as written in my original reply too), so I too would like to see some documentation if indeed these ARE official tests...
Then, Brian: unfortunately those are not mine, these are just some pictures I have kept of some of the specimens I've seen. I've always given these casings a low priority as I do not really collect trench-art like items. But... I think I'll buy one of them the next time I see one cheaply; they're neatly done, and it helps that they are official commemorative items. Several more Japanese official commemorative items (made out of ammo parts) exist, one of the best known examples being the 1" Nordenfelt projectiles that have official engravings and a stamp, commemorating the Taisho enthronement, that were subject of a different thread here some months ago.
I too wonder how they got it so nicely squared; it must have been done with great force, I'd say. Judging from the vast amount of these casings being around, and them all looking just about identical, I'd guess they had made/used some sort of special press for this.
Cheers,
Olafo