TUBATA -THE SALERNO METHOD
Giuseppe Salerno
Giuseppe Salerno was born on December 18th 1862.
Enlisted on February 2nd 1881, he quickly became Chief Armorer Sergeant of the 76th Infantry Regiment, thanks to technical studies carried out previously.
On July 3rd 1892 he was promoted to Chief Technician, 3rd Class and sent on the 6th of the same month with the Italian contingent to Massawa, as technical chief in charge of the maintenance and refurbishment of weapons in the Eritrean colony.
In 1894 he was at the Direzione d'Artiglieria of the Venice arsenal, where he remained until 1898, when he was moved to the Terni Arsenal, where he remained until 1921.
Here on 1 August 1907 he was appointed Chief Technician 1st class.
From 1921 to 1926 he was at the Rome Arsenal as Principal Chief technician.
In 1936 he was appointed Grande Ufficiale della Corona d'Italia.
Practically all the rifle barrels mod. 91 produced in Terni in 1912-1919 have his mark of approval (S.G.), therefore he is anything but a secondary character in terms of the manufacturing and development of the carcano System.
DEVELOPMENT
1912-1917 Patents
1912
On November 21st 1912 Salerno filed a patent for the "tubing or retubing of the barrels of firearms", in which he illustrated a very simple and ingenious method for "Restoring the bore of firearms into its precise shapes, when these shapes are been altered either by corrosion or by natural wear resulting from use".
The process essentially consisted of drilling the worn barrel to approximately 9.2mm, with an enlargement at the height of the cartridge chamber of approximately 14mm.
A steel tube that respected this profile externally (around 9.198 mm, of equal diameter from start to finish) was then milled and drawn, drilling its center at 6mm, and delicately forcing it into the worn and drilled barrel.
At this point the process consisted in making the tube adhere completely in position to the barrel and the chamber with the use of two special double cone-shaped tools approximately 0.16mm wider respectively than the chamber and the barrel of the just inserted tube max specs.
These were forced into the chamber and into the barrel respectively, making the tube adhere completely to the worn barrel, and cutting off any leftovers.
1915
In the midst of the ongoing World War, with a patent filed on November 22, 1915, Salerno further developed his method, with the following procedures:
- An additional reinforcing step was added to the method
- The procedure for obtaining the steel tube to insert into the worn barrels was modified, with instructions for milling and drawing it directly to the dimensions of the perforated barrel, including the cartridge chamber and the new step.
In fact, in the previous method the tube had a constant diameter from start to end, and was widened specifically for the cartridge chamber, exclusively by forcing it with the double-cone tool.
- A new tool for the procedure was illustrated, which will replace the double-cone tool previously used. This new tool consisted of a steel rod with an olive-shaped enlargement at its end, the purpose of which is to forcibly widen the tubing making it adhere completely to the barrel.
1917
Subsequently, Salerno filed a new patent on 9 January 1917, depicting the entire process, with new details and new drawings indicating the accessory tools developed and produced in the meantime to standardize production.
In fact, Salerno had noticed that the tubes during the drawing process tended to break if not cooled at the right time and in the right place, so he implemented a special tool to cool them as they emerged from the drawing process (fig.9).
To this process he also added that the rod with olive for forced widening of the barrel had to be moderated with the use of a dynamometer (fig.5), so as to keep the applied force constant and prevent the maximum effort from being exceeded established for the proceeding (sic).
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First World War - Carcanos with the "Tubata" barrel
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Sources from former Terni employees, collected by other authors over the years, would indicate that they followed the Salerno 1915-17 patents.
Riepe in his book claim that, unlike the patents filed by Salerno in 1912 and 1915-17, the mod.91 rifles during and after the First World War would have been tubed with a slightly different method, basically drilling and tubing the barrel from the muzzle, leaving the chamber untouched except for the shoulders. Another big difference is that the gun would have been drilled at 10.9mm, instead of the 9.3 used by the Patent and by Terni workers' notes.
PRODUCTION AND USE
The Salerno Method for Tubing barrels was used by the Italian Royal Army from the end of 1915 to the end of the conflict to sleeve the 10.4mm barrels of the Vetterli mod. 70/87 to 6.5x52, adapting them to the new 70/87/15 standard.
Subsequently it was also adopted to retube the barrels of rifles mod. 91, probably already during the war, since Terni put an entire laboratory, the 3 bis under Salerno just for tubing barrels; certainly the process was carried on in the early 1920s.
Specifically we know that already in 1917 (Esperienze e studi in corso sui materiali di artiglieria, armi portatili e bombe, alla data 25 Agosto 1917) there have been experiments by the Rome Arsenal for its use in the actual production of the barrels of the 91, using soft iron barrels with a steel tube core (much cheaper in terms of materials used and simple to work) to save in every possible way on the special steel used for the barrels of the 91.​
After WW1 the method was used by the Finnish Army to re-sleeve some of their old M91 Mosin-Nagant rifles into P26 standard, with the barrels marked with the "S" stamp, indicating the Salerno Method.