Pushka Granatë (Polici) 1934
Zog's Albanian gunsmiths take the grenade launcher portions of the M1928 Tromboncino, parts from other older Carcano rifles, and a new stock design (influenced by Jack's future knowledge) to create this bastard. Outside of the stock, only the sights would have to be made from scratch as the PuG uses slightly more powerful ammunition than the Tromboncino in an effort to gain more range/use heavier ammunition. I was also toying with the idea of having an optional bipod/tripod to enable the weapon to function more like a light mortar. Though it would certainly be possible for a single soldier to use this weapon, I was thinking that they would essentially function as a crew served weapon with at least one other soldier serving as the loader/spotter/ammunition carrier.
Just to repeat what I said earlier in the thread. I do not think this weapon would be an equivalent to the M79 or the Japanese Knee Mortar. Even the "boosted" projectiles in TTL would be smaller than the knee mortars (or any other similar light mortar) and have less range. There's a reason Jack's so keen on getting real mortars shipped in from the Italian equipment captured in North Africa, these weapons do not truly replace proper mortars, nor were they intended to.
Why bother then? Here's my/Jack's reasoning:
1. They're cheap. Only the sights/stock needs to be made from scratch. Even 1920s Albania can manage that. The Italians are essentially giving these weapons away since the Albanians are sending the converted rifles back to Italy.
2. They fly under the radar. Remember that prior to 1939 the Italians basically run the Albanian Army (more or less). These weapons allow Zog to give his loyalist forces additional firepower without the Italians caring.
3. Fighters trained to use the PuG can be transitioned to using proper mortars with a bit less effort than training from scratch. (Feel free to correct me on this one!)
4. They're a great weapon for a guerilla campaign against the Italians. They require no special rounds to fire outside of the grenades themselves and are easier to use than a standard mortar. They're more accurate than throwing hand grenades and have a bit more reach, plus they're easily cut down/concealed. Again they're not really going to be competitive anywhere but Albania from 1940-1942 fighting the Italians and Serbs. Nobody's going to be copying the design in WWII, but Zog/Jack can probably use it as the basis for a proper M79 clone post-war.
The only real problem will be supplying the grenades themselves. As mentioned earlier, these supply problems are the main reason Behije gets killed by white-phosphorous chemical burns in TTL. Zog's loyalists mostly burn through pre-war stockpiles during the fighting from June-October 1940 and the next year's fighting in spring / summer 1941. Zog and the British set up a production line in India using the exiting machinery evacuated from Albania which is up and running by 1941 but it takes a while for deliveries to arrive. A few more types of grenade are developed with British/American resources during this time including a new HE round with composition B. These new rounds begin to be stockpiled in Late 1941 in preparation for future offensives...
I have neither the time nor inclination right now, but from my brief research it seems like the 11.43x55 Ottoman rounds used by the American made Martini-Henry rifles beloved by Albanian elders prior to WWI produce a similar amount of power to the 6.5mm Carcano. With a bit of machining, I'd wager something similar to the Tromboncino grenade launcher cup could be mated to an old Martina to produce a slightly less effective weapon similar to the Blanch Chevallier design pictured below which was designed in 1917.