Macchi C.205 - Italian Social Republican Users

The Veltro was also used by the fascist Italian Social Republic which dominated mainly the northern part of the country.
In total twenty nine Veltros made it to the northern airfields when the armistice was declared and Macchi themselves finished the third series with 72 airplanes more before the production was cut down in May 1944 due to allied bombing as the factory was bombed.
The first action with the Aeronautica Nazionale Repubblicana was on 3rd January 1944 when a formation of Veltros, that had still German markings, attacked a formation of Boeing B-17 with their escort of P-38 Lightining. Later, on 24th January, they were transferred to Friulia and on 28th they shot down their first American four engined B-24 Liberator bomber.
They served mainly with the 1º Gruppo (first squadron) and the 3º Gruppo (third squadron) received also some of them. They were scattered through smaller units.
Generally, they served well with the RSI as most of the units were homogeneusly equipped and were guided by German radars. Even if they weren't many, they achieved managed to inflict a respectable amount of losses to Allied bombers and fighters.

Sources:
1. https://en.wikipedia.org/wiki/Macchi_C.205
2. Salamander Books - The Complete Book of Fighters