Diana Model-30 Military Trainer - 10/1939.
Here are some pics of a decent example of a 1930s mod 30 military trainer, dated 10,39.
The first thing that strikes you when you hold one of these rifles is how dainty it is. Its length, 42 inches (107cm), isn't especially petite but the cylinder is narrow and the rifle is suprisingly light.
The second thing you notice is the high quality of the detailing. The rearsight is the block and element type, also found on the model 26 underlever (see <a href="http://www.network54.com/Forum/664382/thread/1298739889/Rear+sights+comparison+-+Diana+26+and+HW50">this thread</a> for a discussion of this sight). The front sight has a ramp that is nicely grooved, to reduce glare, and is extremely solidly made. The front sling band is made of incredibly thick, blued steel and the short cocking lever is solid steel.
In terms of the build quailty and detailing, it's quite similar to the Haenel 33 Junior, which it was in competition with at the time. Perhaps the presence of the other encouraged these companies to "raise their game" rather than build down to a price, which must have been tempting.
I haven't done a velocity check or taken a look inside the cylinder yet, but looking at the small swept volume I would imagine that even operating at its maximum potential this is a low-powered rifle. No doubt it would have seemed very impressive to a (Hitler?!) youth on the parade ground, but as a serious military firearms trainer it can't have been much of a performer.
Here are some partial stripdown pics: