New Jap 40mm mortar?

[HAZORD]

No, not really. Sorry to lead you on, but I wanted to show the Jap 40mm HO301 Aircraft round next to some 50mm Knee mortar projos. I picked up the HO301 around 20 years ago, and the collector who sold it to me told me that he had gotten it from a gentleman that thought it was a knee mortar round. Here in the western U.S., 50mm knee mortar stuff is fairly common, so if you already have what you want, you tend to ignore them as you hurry through the show looking for new treasure.

So, my thesis is, that you should look carefully before making a snap judgement about a piece of ordnance.

Starting on the left, is a 50mm smoke projo, followed by some HE projos, one obviously repainted (not by me), and lastly the 40mm HO301 complete Aircraft round. The final photo is a closeup of the smoke shell fuze.

The AC round is very similar to the mortar projos, in that it has a primer in the center of the base, which is perforated. The propellant gasses exit the perforations and do their thing. The AC round differs from the mortars, in that it has a fixed rotating band, whereas the mortars have a band that expands out to engage the rifling when the propellant is ignited.

All items empty/inert

John

 

[BOMBSaway1980]

are those orginal paint on the 50mm knee mortars those look really good

 

[BMG50]

Nice kit jap stuff, i have a knee mortar round but missing the pin.

 

[SG500]

OH MY!!!!!! I've been after a HO301 for years, you may even have spotted one on my wants list. That's a nice round, needless to say if you bump into any more gents who have any of these spare I'd be very interested.
Thanks for showing it.
Dave.

 

[Falcon]

What aircraft was the H0301 fitted to?

 

[HAZORD]

Going through Tony Williams' "Flying Guns WWII", he says the HO301 was used in the Ki-44-IIc model, with two guns mounted in the wings, along with 2 HO103 (12.7mm) guns in the nose.

These guns fired from a 10 round magazine, and had a high rate of fire (450 rpm), but slow muzzle velocity (246 m/s), so it was really only effective on bombers.

As far as paint quality goes, I think the round second from the left is a partial repaint. The red nose looks original, but the body stripes look like they were added. The paint stripes are too thick. Normal Jap paint is very thin laquer-like.

 

[Bonnex]

Ho301

I have scanned a leaflet on the Ho301. Usual place.

What aircraft was the H0301 fitted to?

 

[HAZORD]

Thanks Bonnex!

I pulled the section drawings out of your leaflet and atached below. It was interesting to see that they had such a high dud rate, and the leaflet says the magazine holds 15 rounds instead of my other sources that say 10. I guess I need to find a 20mm gaine for my fuze.

 

[Bonnex]

Ho301

Thanks Bonnex!

[...] leaflet says the magazine holds 15 rounds instead of my other sources that say 10. [...].

Thanks. I recommend caution about facts in these leaflets (and the Tech Reports), particularly if they are 'Issue 1'. They were got out to the field pretty quickly after initial exploitation of the munition for the guidance of IOOs (ATOs). Some assumptions will be wrong. If there is a discrepancy against later work I would tend towards the later evidence.

 

[Falcon]

Going through Tony Williams' "Flying Guns WWII", he says the HO301 was used in the Ki-44-IIc model, with two guns mounted in the wings, along with 2 HO103 (12.7mm) guns in the nose.

These guns fired from a 10 round magazine, and had a high rate of fire (450 rpm), but slow muzzle velocity (246 m/s), so it was really only effective on bombers.

Thanks for the info, I didn't realise until I looked it up that this was a caseless round with the propellant in the base.

I thought the round shown was simplay a projectile minus case.