You can get a kit from Perazzi in a small case, 2 spare springs, firing pins and their little coil springs, and a tool to compress the spring for the MX8.
As a retired ISSF A Clay Target Judge with 20 years experience of World Cups, Grands Prix and 2 Olympic Games, I have only ever experience a shooter with a broken spring once, one of the USA Shooting Team Trials broke a spring in practice. I would imagine the coaches put new springs in before a big match.