[pbleed]

Rick,
Thank you for your comments. You are correct is saying that these tubes do not have direct means of elevation. Perhaps they were used with an element that ain't there now. I also wonder if they were intended for direct fire from a prepared situation much as coehorn mortars were, but instead of shooting a "up" they may have been intended to for direct, short range bombard
Both of these guns had the breech plate set into and all the way through the base so that they have a large bolt/nut protruding from the base. They do NOT sit comfortably on a hard flat surface.
The 37mm round you showed us is one of the enhanced anti-tank rounds. The first generation 37's - as used in Manchuria and them thru out WW1 - were simply cylinders.
Please excuse the shortcomings of these images of what I will call the "Lantaka"
First the muzzle. Note that it is essentially flat, but that it has a cast front site.
Next consider the breech from the top. My interpretation is that instead of simply cutting the end of the barrel off, the shortening was done to leave a "barrel extension" that would lock into the breech plate. In this view the gun is closed with a replacement brass pin since the original ain't there.
Okay, now take a look down the barrel. Note the cartridge extraction system.
Next look at the rear of the gun. Two things catch my eye. First, look at the feature at the extreme back end of the barrel extension. Do you see it? I have to wonder/guess that this may somehow be a remnant of the touch hole of the original "uncut" lantaka. It is easier to also see that this gun has a forges iron ring driven into the base. Clearly, it could have been tied down in position. There appears to have been another of these fixtures on the other side of the rear surface. There appear to have been a pair of them in the front of the base as well, but they ain't there now.