This excellent article was excerpted from the web site www.forgottenweapons.com. I've removed photos and two .pdf documents from this text. Neither opened easily from within the text. Instead I've posted them below. "The Villar Perosa was a rather odd weapon developed by noted designer Revelli in Italy in 1914 and adopted into service in 1915. It was a basically a pair of open-bolt submachine guns (pre-dating shoulder-fired submachine gun designs, interestingly) mounted side by side with a set of spade grips. It had an extremely high rate of fire (1200-1500 rpm form each barrel), and was initially intended for use on aircraft, against other aircraft. However, it was quickly made obsolete in this role by improvements in aircraft durability. It was also adapted to serve as a ground machine gun. Of course, it also suffered from having no practical grip or stock. The most common practice when using the gun in a support role was to fire one barrel at a time, while an assistant gunner changed magazines. Used this way, a more continuous fire could be maintained – although a single 25-round magazine would take no more than a single second to empty. The tactical role of the Villar Perosa changed throughout the war, as it was tried in different combat situations and soldiers developed more effective ways to exploit its strengths and avoid its weaknesses. In its intended use as a light machine gun for infantry support is was a failure due to its lack of range and small magazine capacity combined with its high rate of fire. It was more successfully used by Italian alpine troops, who lacked any other machine gun that was portable enough for mountain use. Eventually, tactics were developed to use the Villar Perosa in walking fire (like a BAR, actually) with a sling or harness. However, the final use of most Villar Perosa guns was to be broken down and their components used to build M1918 submachine guns by adding wood stocks, forearms, and conventional triggers to single-barrel halves of the gun. Most references to the Villar Perosa describe it as being chambered for the 9mm Glisenti cartridge, but we have found (and made available for download below) a manual in English which specifies the use of 9×19 Luger for the gun. The two cartridges are effectively identical in physical dimension, with the difference lying in powder charge. Some of the Villar Perosa guns were made in Toronto under contract with the Italian government – perhaps these Canadian guns were proofed for 9mm Luger? Or perhaps the reference is simply an error. We don’t know, but we’re looking for more information."