I recently received an older brochure (no date) on Tigullio spearguns and have attached some of the images here for interest. I have never seen the "Sagittario" pneumatic gun, so its inner works are a bit of a mystery beyond what the layout diagram shows here. It appears that it is a forward latching speargun as the balls (part 4) in the muzzle fit into (I assume) annular notches in the shaft of which there are three at varying distances from the front end of the shaft. So you change the power of the shot by inserting the spear further into the gun and locking it at one of these three alternative positions to vary the propulsion stroke of the inner barrel piston in each case. If this is how it works then the problem with such mechanisms is the shaft controlling balls (usually three) are exposed to saltwater and they gradually wear out, so the gun will not latch correctly when the balls no longer slide smoothly in the mechanism slots that control their positions, either held in tightly against the shaft notch (cocked to shoot) or retracted to allow the shaft to escape the gun during the shot. The front barrel appears to have a sprung loaded sleeve that slides back and forth which is released by pulling the trigger and this sleeve in turn controls the position of the balls in the muzzle. It seems a very novel idea, but it works better when the balls, which act as a collective sear tooth grouped in a ring arrangement around the inner barrel, are located down the rear end of the gun where they are inside the compressed air reservoir. That way the steel balls are always enveloped in oil such as they are in the GSD "Punto" pneumatic guns which have three balls inside the rear end of the air reservoir functioning as the piston controlling sear tooth. As the "Sagittario" has them located in the muzzle on the front end of the barrel (which floods when you cock the gun) its barrel sliding piston needs no tail.
Technisub had a "Drago" pneumatic gun that also worked the same way, but the three balls in the "Drago" (and the smaller pistol layout "Pulce" version) muzzle were controlled by a pull rod external to the body or tank tube and located on the bottom of the gun. On the "Drago" model you could slide the moveable plastic grip handle back and forth and lock it up at different positions on the gun body (and also onto the trigger controlled pull rod) so that you had the option of using it as a mid-handle or a rear handle gun. The "Sagittario" gun may be of a similar vintage to the "Drago", but until I saw this brochure I had never heard of it before. I am wondering if anyone here has seen one and knows anything more about them. The "Sagittario" was apparently produced as a TANA 34" (87 cm) and a SAFARI 46" (117 cm) model. No photo or diagram of the spears is shown, so we cannot see the triple notch spacing on the spear shaft.