Weapons of War: The Italian Quick-Firer

Cannone Da 75/27 Modelo 11 in Transit

By James Patton

During the decades prior to 1914, perhaps the most significant advancement in land warfare technology was quick-firing field guns (“QFs”). Although the French invented them, by 1914 just about everyone had some version in service including many retro-fits. The Italian Army was no exception, with their Cannone Da 75/27 Modelo 11, which henceforth we’ll call the “75/27.”

It might be useful at this point to explain what a QF is. In the mid-19th century cased cartridges were invented for the new family of breech-loading small arms. By the 1880s the chemical and metallurgical glitches had been worked through and there was no obstacle to manufacturing cased artillery shells, even pre-assembled ones.  These would be a huge break through — they would eliminate most of the time spent in charging and loading the field gun. However, there remained the problem of recoil. When the gun is fired Newton’s Third Law of Motion specifies that for every action there is an equal and opposite reaction. Thus, while the projectile is hurled forward the gun breech of the barrel is pushed with equal force, causing the gun (which is much heavier than the projectile), to “jump” backwards. This means that the gun has to be returned to the firing position and “relaid” (aimed again), both time-consuming steps. Led by the French Lt. Col. Joseph-Albert Deport (1846–1926) the first workable recoil absorption devices (also known as "recuperators") used pistons pushing against highly viscous oil, compressed air in sealed chambers and very stiff springs, sometimes used in combination. The design is exactly the same as in today’s automotive shock absorber. 

The “gold standard” QF was the French Canon de 75 Modèle 1897, (“French 75”) which used a hydro-pneumatic recoil mechanism with two pistons. While very effective (the recoil cycle was about two seconds) this design required precise machining and the use of O-ring type seals made from silver to keep the piston chambers from leaking. When the U.S. began to produce these guns under license, very close tolerances were achieved and a good gun became even better. Although rates of fire in excess of fifteen rounds per minute were possible, the barrel would soon overheat and the hydraulic oil would lose viscosity, so in actual use three to four rounds per minute was the limit. 

The Italian army was a little late in entering the game in 1911 when they turned to the French steelworks Compagnie anonyme de Châtillon et Commentry, located in Neuves-Maisons, whose in-house weapons designer was none other than ex-Lt. Col. Deport, who had been passed over for promotion in 1894. He set out to make a QF with a 75 mm (2.95 in.) bore, identical to the French QF, but using a shorter and lighter 6.35 kg (14 lb.) HE shell. The effective range was 10,240 meters, comparable to the French 75’s 11,000 meters. It was lighter than the French 75, 1,015 kg vs. 1,544 kg, an important difference in mountain warfare.

Knowing the limitations of machining at Fabbrica Armi Esercito di Terni, he selected a hydro-spring dual-recoil system, which featured a sort of lever welded to the bottom of the mouth of the barrel with a paddle on the other end which pushed against a spring inside of a rectangular oil reservoir located about six inches below the barrel and running the entire length of the barrel. This design, although more complicated, avoided the problems of leaking cylinder seals and of barrel heat thinning the oil (which raised the effective rate of fire to fifteen rounds per minute), but it was never used again. 

On Display at Mte. San Michele, Carso Sector

Since Deport had patented a split-trail design in 1908, on his own initiative he incorporated this feature into his Italian 75/27. This enabled it to be elevated to 65 degrees and made plunging fire a viable and deadly option. No other QF in the era could elevate more than 18 degrees and every field gun designed since the 75/27 has employed the split-trail.

The little Italian 75/27 was both obsolescent and futuristic. Total production was 1,341 guns and a few examples remained in service through 1945. The one in the photograph above was on static display at Monte San Michele in Italy in 2006. There is also a specimen in a museum in Finland.