In April 1930, during the 8th session of the Technical Committee for Armaments and Ammunition (CSTAM), under the chairmanship of Admiral Segre, the selection of suitable armament for the fleet’s small ships was considered. The task of replacing the old 2-pounder 40mm Vickers, which had been in service with the Italian Navy since the previous war, was quite urgent.
Strictly speaking, the licensed automatic Vickers-Pom-Pom was not entirely bad, but its complex design, the use of fabric belts, and the insufficient power of its ammunition, coupled with modest ballistic characteristics, rendered this weapon no longer suitable for the times. The stated objective for replacing this gun called for a 37-40mm caliber design with magazine feeding and a more powerful cartridge.
Among the designs considered were projects from the American firm Colt, with a prototype of their 37mm anti-aircraft gun designed by Browning (which would later become the M1 automatic cannon); the French Hotchkiss with its newest 13.2mm Mle 1930 machine gun; the Swiss Solothurn with a prototype of the 37mm S10-100 anti-aircraft gun; and the experimental 37mm Scotti gun model 1931.
During the review of the aforementioned designs, it was decided to create an Italian system, taking the best from each weapon. The Solothurn, at that time still very raw and technologically complex, was immediately dismissed. Alfredo Scotti, who developed his automatic weapon by scaling his combination of a semi-free bolt and gas-operated principle to 37mm caliber, also failed to generate interest, although his hypertrophied machine gun with a 20-round drum magazine looked quite progressive.
Lobbying by the Breda company, which had warm relations with the Duce, also played a role. As a result, this company received the contract to develop the new automatic weapon, basing it on the gas-operated automation of the licensed Hotchkiss machine gun they had purchased. Only one small task remained: to scale it up for the very powerful American Colt 37×223SR cartridge.
Initial Features and Design Challenges
By the summer of 1932, the Breda company presented the first sample of its automatic weapon for testing, featuring a 54-caliber barrel. For some reason, the developers did not fully copy the “Colt” cartridge, instead developing their own, even more powerful 37×232SR. Its 820-gram shell exited the barrel with an initial velocity of about 800 m/s.
A characteristic difference of the Breda 37/54 automatic weapon from its Hotchkiss machine gun origin was that the scaled-up weapon was constructively turned on its side. Thus, the classic “Hotchkiss-style” receiver for a rigid strip magazine was located on top, while the gas tube was positioned parallel to the barrel on the left. This arrangement was made for the prospective placement of guns in twin mounts, where top loading would be more convenient.
A box for two 6-round clips was mounted on the receiver. The barrel had a water-cooling jacket and was equipped with a conical flash suppressor. By adjusting the size of the gas port, the rate of fire could be varied to 60, 80, or 120 rounds/min. The weight of the gun body was 277 kg. The naval twin mount, Breda 37/54 mod 1932, on a fixed pedestal, weighed 4.9 tons.
Aiming of the twin mount was done manually by a crew of 7 people: a commander, a horizontal gunner, a vertical gunner, two loaders, and two ammunition carriers. The introduction of new weapons into production was extremely slow. In essence, the first automatic cannons only appeared on fleet ships in 1935.
A whole host of shortcomings was noted. The long kinematic transmission from the trigger pedal to the firing mechanism was a constant source of failures. Inconvenient access to the receiver for loaders also drew complaints, affecting the practical rate of fire. Furthermore, the system was prone to increased vibration. This was related to the decision to rotate the design sideways, so that the gas channel with its piston was offset from the weapon’s axis. Consequently, the recoil force vector pulled the barrel to the side after each shot. As a result, the rate of fire had to be reduced, essentially to a series of single shots.
Variants and Limited Production
It remains a mystery why the French, when selling the license for their machine gun, did not inform their neighbors about the existence of a Hotchkiss version with a top-inserting box magazine and a classic bottom placement of the gas piston. If the Italians had used this version as a base for scaling, the problem with weapon vibration would have been largely solved.
In 1938, a somewhat improved twin mount appeared, which eliminated water cooling and was slightly lighter (4.2 tons), but the main drawbacks of the system were not rectified. Vibration was somewhat reduced on the single mount Model 1939, in which the gun was finally rotated with the gas tube facing downwards and clip feeding from the left. This 37mm automatic variant was primarily intended as a mobile army anti-aircraft gun, mounted on a single-axle carriage.
For the DICAT (Territorial Defense) forces, both single-barrel Model 1939 and twin-barrel Model 1938 mounts were produced on pedestal carriages, similar to naval installations. Breda 37/54 automatic guns were also encountered in single configurations, mounted on captured Bofors twin-axle carriages. The production rate of Italian 37mm anti-aircraft guns was very low, peaking in November 1941, when the Brescia factory managed to deliver only 21 guns in a month!
By the time Italy entered the war, army units possessed only 310 guns, with another 108 automatic weapons in service with territorial defense forces. After the defeat of Italian troops in North Africa in late 1942, army units accounted for only 92 Breda 37/54 automatic guns. In the rear, at that time, 317 guns of this type were protecting the mainland as part of the DICAT territorial defense forces.
The Breda 37/54 in Italian Aviation
On Italian navy ships, the quantity of these automatic weapons during the war was also clearly insufficient. The largest number of Breda 37/54 anti-aircraft guns was carried by the new “Littorio”-class battleships—20 pieces each in twin mounts of models 32 and 38. Older “Andrea Doria” battleships carried 12-15 guns. Cruisers only carried 4 twin mounts, and destroyers were initially not equipped with them at all. Only during combat operations did some receive one twin mount and sometimes another single one, by dismantling other armament.
The 37mm Breda automatic gun also featured in attempts by the Regia Aeronautica leadership to equip Italian aviation with powerful weapons suitable for both ground-attack operations and combating enemy bombers. These attempts were embodied in several Italian aircraft models. One of them was the multi-purpose twin-engine CANSA FC.20. Initially designed before the war as a reconnaissance aircraft, it did not attract interest from the Italian Royal Air Force.
In an attempt to save the project, the company developed a modernized variant, the FC.20bis, with a redesigned nose section where the body of the 37mm Breda anti-aircraft gun was placed instead of the navigator’s cockpit. This version of the aircraft was considered a fighter, attack aircraft, and light bomber. The cannon was moved as far back as possible, located under the pilot’s feet. Behind the pilot was the second crew member, who served as a radio operator/gunner, operating a Scotti turret machine gun and simultaneously loading the Breda cannon.
In the FC.20 fighter, the loader’s position was simply pathetic: he was on board the aircraft behind the pilot in an uncomfortable cockpit, topped with a portable rotating machine gun turret, and practically straddling the gun, he had to manually insert new clips into it. Turning around there, operating standard 6-round clips weighing 12 kg each, was very difficult. The career of the cannon-armed FC.20bis, of which only 7 were built including the prototype, was not rich in combat episodes.
Only once did the commander of the 22nd Group, Major Corrado Ricci, try to use the aircraft in combat, attempting to intercept a formation of American Liberators on April 10, 1943. Ricci flew a parallel course to them, 200 meters higher. Choosing the last aircraft as his target, the pilot turned to attack, but his maneuvers were too sharp, leading the FC.20 to immediate autorotation. After recovering control after one loop, Ricci found himself at the tail of the enemy formation, coming under concentrated fire from their tail gunners.
For a moment, he managed to catch two bombers in his sights and fired several shells at them which, unfortunately for the Major, missed. After the flight, Major Ricci explained his failure to hit: low speed at an altitude of 7500 meters combined with instability during firing made hitting the bombers impossible. This flight was the “bloodiest episode” in the FC.20’s career as an interceptor.
Shortly before the capitulation, CANSA released an improved modification of the aircraft, the FC.20ter. In it, they tried to correct the inconvenience of servicing the gun. On the FC.20ter, the 37mm gun was moved as far forward as possible, with the loader’s position placed in a new glazed nose cockpit in front of the pilot’s seat. However, this aircraft remained a single prototype.
Even less successful was the project of the Savoia-Marchetti SM.89 anti-ship strike aircraft. Developed based on the three-engine SM.84 torpedo bomber, this aircraft featured a two-engine configuration and, in place of the eliminated third nose engine, had a powerful gun battery consisting of a pair of 37mm Breda 37/54 cannons and three 12.7mm Breda-SAFAT machine guns. Tests of the single SM.89 prototype, which clearly lacked power, were conducted until April 1943. At the end of these tests, the aircraft was assigned to the 173rd Squadron for operational trials.
This unit, based at Cerveteri airfield near Rome, provided air defense for the Italian capital. This Strategic Reconnaissance squadron became, in effect, an experimental unit, also adopting several pre-production cannon-armed CANSA FC.20s in addition to the SM.89. At this point, the traces of the SM.89 are lost, and despite the General Staff’s desire to use the SM.89 to counter the Allied landings in Salerno, this aircraft never saw combat. Officially, it was not adopted, and in all likelihood, the single SM.89 was scrapped after the armistice was signed.
Overall, the Breda automatic gun can be characterized as an unsuccessful project. Although the weapon possessed decent ballistics thanks to its powerful cartridge and a barrel life of up to 1.5 million rounds, vibration problems continued to plague the anti-aircraft gun until the very end of serial production. Although the formal effective range was up to 7.8 km, and its altitude reach up to 5 km, in reality, aimed firing at such distances was akin to shooting blindly.
Therefore, Italian anti-aircraft gunners preferred to conduct unaimed barrage fire, hoping more to disrupt an attack than to achieve a hit. Archaic manual aiming further compounded the shortcomings. Shortly before the end of the war, the navy launched a program to replace the rapidly obsolescent 37mm Breda with more advanced 65mm automatic cannons, but this only resulted in the production of a few experimental prototypes from various companies. After the war, the 37mm Breda was very quickly removed from service.
Technical Specifications
| Modification | 37/54 mod 32 |
| Caliber, mm | 37 |
| Type of automation | gas-operated |
| Mass, kg | 277 (gun body) 1970 (in anti-aircraft configuration mod.1939) |
| Length, mm | 3280 |
| Barrel length, mm | 1998 |
| Rate of fire, rounds/min | up to 140 |
| Muzzle velocity, m/s | 800 |
| Magazine capacity | 6-round clip |
| Projectile mass, g. | 830 |
| Ammunition type | 37×232SR |
Image and diagram gallery of the Breda 37/54
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