CB-M2 submachine gun from Benelli
The CB-M2 submachine gun from Benelli. While it may not look like much at first glance, it's actually quite unusual. weapons...
A country tormented by the passion of fate!
Mistress of all fatal centuries!
The peoples honored you like slaves,
And emperors are like children.
You judged the world from the throne of the Caesars
And a bigger world from the Vatican.
Your former power is a fallen idol,
But humanity is drunk with your past.
Your artists on the fragility of the canvas
Captured dreams that will never happen again!
"Italy". V. Bryusov
Mistress of all fatal centuries!
The peoples honored you like slaves,
And emperors are like children.
You judged the world from the throne of the Caesars
And a bigger world from the Vatican.
Your former power is a fallen idol,
But humanity is drunk with your past.
Your artists on the fragility of the canvas
Captured dreams that will never happen again!
"Italy". V. Bryusov
Weapons and firms. Valery Bryusov wrote some very good poetry about Italy. He rightly observed that Italy knew how to surprise in the past, and it still does today, including in the field of weapons production. And although not all Italian gunsmiths' designs are mass-produced, and some are known only to specialists, the latter are often very interesting and original. One such example was created by the Italian arms manufacturer Benelli. Founded in 1967 in Urbino, the company primarily produces rifles and shotguns, which are used both by the armed forces and sold on the civilian firearms market. Since 2000, the company has been owned by Beretta.
However, even before this acquisition, Benelli designers had created a submachine gun with completely unique characteristics. It weighs 3,4 kg unloaded. Its length with the stock folded is 450 mm, and with the stock extended, 660 mm. The table is 200 mm long. Its rate of fire is approximately 800-1000 rounds per minute. The magazine capacity is 30 rounds. Everything seems normal, but in fact, this is a very unusual weapon, developed by Italian designer Bruno Civolani. He used it to develop the concept of a cartridge with a "flying case," which is sometimes not entirely accurately referred to as caseless. The prototype proved to be quite functional, but the military was never satisfied with it, and the program was canceled sometime around 1985, and the submachine gun never entered production. However, Civolani's "machine" turned out to be quite interesting.
The fact is that all muzzle-loading percussion rifles (and pistols), despite all their shortcomings, had one major advantage over cartridge rifles and shotguns: they didn't "produce" spent cartridges when firing! Modern rapid-fire, and especially automatic, weapons require a great many of them. Moreover, they still haven't learned how to collect them in large quantities on the battlefield.
In short, every shot involves not only a bullet leaving the barrel but also a cartridge case made of expensive non-ferrous metal, which is lost to the elements. Cases are available in both steel and bimetallic versions, which are cheaper but generally of inferior quality. Therefore, it's not surprising that gunsmiths attempted to create cartridges from these cartridge cases. They did, and they succeeded, but not very well. First, the problem of protecting the bullet's powder charge from mechanical impact was never solved. Second, it was never possible to completely eliminate its spontaneous ignition in the chamber heated by firing. Third, it turned out that these cartridges were difficult to store due to their greater susceptibility to atmospheric influences. Caseless cartridges also had another significant drawback. The bullet was contained within the powder charge—and if a misfire occurred during firing, how could the defective cartridge be removed? What could it be hooked onto to push it out of the chamber? Obviously, the extractor tooth couldn't hook onto the powder charge itself, as in a cartridge-based weapon. But then what?
They tried to create a liquid-fuel weapon. It was also essentially caseless, but the situation with it was even worse. Thus, a third "economical system" of small arms was born, using a cartridge with a "flying case." These cartridges still contain a case, but it is connected to the bullet and lacks the base with the primer. That is, the case is not sealed at the back, and the powder charge inside is sealed in this very spot with a burnable plug or a layer of special varnish. It's worth noting that in this case, the powder charge never comes into contact with the chamber, which is heated by firing. The case walls also reliably cut into the rifling of the barrel and guide the bullet along them. However, the bullet exits the barrel along with the case, since they form a single unit.
Thus, a special cartridge, dubbed the 9mm AUPO, had to be developed for the Benelli submachine gun. It consisted of a solid metal head and a hollow, thin-walled, cylindrical rear section. This rear section of the cartridge served as the cartridge case, housing the propellant powder and the igniter charge. The open rear section of the cartridge case was sealed by a special combustion diaphragm, which also protected the propellant from moisture during storage.
Overall, this design was very similar to that of the Volcanic pistols and rifles*, which appeared in the second half of the 19th century and were manufactured by Horatio Smith and Daniel Wesson. The main differences lay in the bullet material (it was solid lead), the propellant powder, and the location of the primer cap. Benelli's cartridges used smokeless powder, and the primer charge was located not behind the bullet, but at the front of the cartridge, immediately behind it, in a special annular cavity. The Volcanic suffered from the same extraction problem as other caseless cartridges of later times. True, it did have a pair of "hooks" on the front of the bolt, which were supposed to extract the lead cartridge from the chamber. However, in practice, this "extractor" functioned unreliably.
The design of the 9mm AUPO cartridge-bullet from Benelli: the breech-piston is shown in pink, the propellant powder charge in gray, the initiator charge in red, the firing pin in black, and the bullet itself in yellow. Fig. by A. Shepsa
In any case, the Benelli cartridge was far more sophisticated and sophisticated. The primer charge was ignited by the striker striking the cartridge wall where the primer is located. The cartridge case wall isn't completely pierced, but only slightly deformed, as is typical with rimfire cartridges. Because the ignition occurred from the front rather than the rear, the propellant charge burned completely in the barrel, and the bullet, accordingly, ejected along with the cartridge case and flew toward the target as a single unit.
The CB-M2 submachine gun extraction system: 1 – bolt-piston, A – bolt face, 2 – bullet with case, partially cross-sectioned, 3 – cartridge being fed, 4 – cartridge being fed into the chamber, 5 – cartridge in the chamber, bolt fully inserted into the chamber, 6 – no shot fired, when the bolt is pulled back, it moves back, extracting the misfired round from the barrel, 7 – with further rearward movement of the barrel, the misfired round is removed through a window in the lower part of the receiver. Fig. A Shepsa
The lack of a base on the cartridge case necessitated a more thorough obturation during firing. To this end, the submachine gun's chamber was made very long, so that the entire front section of the bolt entered the chamber before firing. A very original solution was provided for extracting misfired cartridges. For this purpose, a special catch was installed on the bolt face, which engaged a ring flange located inside the rear of the cartridge case. This was both reliable and convenient—at least, much better than systems with completely caseless cartridges. The misfired cartridge was then ejected through a downward-facing port in the receiver, located behind the magazine well. However, due to the specific ignition system, the firing mechanism had to be positioned above the chamber, resulting in a characteristic "hump" on the receiver cover. The L-shaped firing pin lever was located above the barrel and chamber, and the firing pin itself passed through a vertical channel in the chamber wall and, after the cartridge was fully chambered, struck the chamber wall near the primer. The cartridges were fed from standard detachable box magazines. No specific defects have been reported with this submachine gun. However, one might suspect that when firing it, the amount of propellant gases entering the receiver from the barrel is significantly greater than in a weapon using cased ammunition. And if the propellant used has poor combustion properties, this design will require more frequent and thorough cleaning!
* Interestingly, this rather amusing weapon, despite everything, has even been featured in films. For example, the Volcanic carbine can be seen in the 1965 western "For a Few Dollars More" by Italian director Sergio Leone. Clint Eastwood's character uses it. It also appears in the 1987 Hong Kong action film "Magnificent Warriors," set in Japanese-occupied China in the second half of the 1930s. And in "The Man in the High Castle" (USA, 2015), it's simply hanging on the wall of an antique shop. It's a shame the Italian submachine gun wasn't so lucky in this regard...
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