So my dad worked with a WW2 vet who was in the pacific theater and received this as a gift. He said it was a Japanese mortar he picked up in WW2 but I haven't been able to find much information on it. It's small, maybe 6 inches in length, and has what looks like japanese characters on it. it unscrews in the middle, opposite way of course. clockwise to unscrew and counter-clockwise to unscrew. the top pushes down which is how I'm guessing mortars work. Once it hits the ground the pin ignites the charge inside. I'll post some pics View attachment 12588
Looksl ike a Type 89 Japanese 'Knee Mortar' it doesn't appear to be 50MM though. Can you throw a micrometer on the widest part? Japanese 50mm Knee Mortar - Inert-Ord.net EDIT: Went back a few pages on the above link and found this: Japanese 40mm Air Dropped Cluster Muniton. Your's looks to be missing the fuze mechanism. http://www.inert-ord.net/jap02h/t2sub/index.html
Yes. I was going to say that the Type 89 "Mortar" was really a grenade discharger. It didn't fire a mortar bomb but rather either the Type 89 or 91 grenade.
The Type 98 50mm Mortar was a weapon used by Japanese Engineers to clear a path through barbed wire, I am not sure about its ammo but it may be a spigot round attached to a Bangalore torpedo.
Its two type 88 fuzes fitted together to make a souvenir/trenchart I dont know much about Japanese stuff but i think the stumpy fuze is a type88 short delay fuze with the fuze lower portion and boosters removed (see drawing) to allow the pointy type88 instaneous fuze to be fitted.