Bruno Civolani, Italian Gunsmith Legend

The name of the Italian engineer Bruno Civolani is well known in arms circles. It was thanks to his developments that many of the self-loading shotguns popular today were created. The inertia bolt he invented is now widely used by arms manufacturers around the world.

The inertia spring, located inside the bolt frame, became a kind of “Heart” of the scheme developed by Civolani.

The compression of the spring formed an energy impulse that set all the systems of the mechanism in motion. The energy of the powder gases, acting on the bottom of the cartridge case and the bolt, initiated the release of the combat projections of the bolt larva from the counter stops.

The longitudinally sliding rotary larva began to move along the copying cutout located on the bolt frame, thereby compressing the inertia spring. When the spring was released, its impulse pushed the bolt back. The bolt tail acted on the return spring located in the butt, compressing it. The return action of the return mechanism placed the bolt at the starting point. As it moved, the next cartridge was picked up and fed into the chamber.

Thus, the automatic weapon used the energy of the shot acting on the bolt group, with a stationary barrel and no need to divert powder gases.

The peculiarity of Civolani’s approach to the design process was constant experimentation. He knew how to use a drawing board, but instead of calculations and drawings, he preferred to work on machines. His scheme was simple in essence, but the complexity of producing a gun with inertial automation lay in the precise selection of the spring force relative to the dimensions and weight of the parts of the bolt group.

In addition to the accuracy of the calculations, the process required a high level of metalworking and was accompanied by a large waste of materials.

As a result, after the creation of the first prototypes, Civolani had difficulties finding funding to launch his gun into production.

Civolani found an investor in Giovanni Benelli, who became interested in his design, and the Benelli Armi company launched the Civolani shotgun, which became known as the Benelli 121 model.

It was the first in the extensive family of inertial shotguns manufactured by Benelli. Serial production lasted from 1967 to 1973.

During this time, the design underwent a number of changes, as a result of which the operation of the automatic system became 100% reliable. The minimum weight of the shot charge of the cartridge was 24 g, the “upper ceiling” was determined at 55 g. The first years of production of the shotgun used 12×70 mm cartridges, later versions in 20 gauge appeared.

A 5-round ammunition load could be fired in 1.2 seconds. The forged barrels were produced in Saint-Etienne, France, the receivers were made of gun steel. The shotgun was supplied in three versions: Standard, Lux, Extra Lux, distinguished by decorative finishing.

In 1999, Civolani developed a new automatic scheme based on the use of the energy of powder gases. Through the side holes in the barrel bore, part of the gases are diverted into a paired piston chamber, and their energy acts on two pistons, which with their rods set the bolt group in motion. The embodiment of the new scheme was the Benelli M4 Super 90 shotgun. After its adoption by the US Army, the name of Civolani gained worldwide fame.

Bruno Civolani brought his last project to serial production at the age of 84. Under a contract concluded with the Breda company, he created a model of the Breda Xanthos inertial shotgun. Its uniqueness lies in the design of the bolt and the cartridge loading system. Unlike all previous developments that used a longitudinally sliding rotary bolt, the Xanthos is distinguished by the use of a wedge locking principle. The combat wedge has a surface made in the form of a segment of a circle and enters a mating groove located on the barrel shank.

The advantage of a bolt of this design is the ability to support it by hand when loading a cartridge into the chamber. In driven hunts, this prevents the occurrence of a clang that can scare off an animal. Manual loading is unacceptable on any type of weapon equipped with a rotary bolt. Attempts to do this are fraught with incomplete closing of the chamber.

Bruno Civolani passed away in 2008 at the age of 90. Despite the fact that he made his main achievements in the field of smoothbore weapons, their importance should not be underestimated. It is thanks to him that modern shooters and hunters have a large selection of excellent inertial guns.

The address of the original article about Bruno Chivolani is https://guns.club/lib/history/italyanskiy-konstruktor-bruno-chivolani/