I have the spring kit in my C100 and have over a thousand rounds thru it and have only had 2 fail to fire on some S&B same box same day, I think it was due to some extra hard primers. It has been flawless since and that was probably 800 rounds ago.
I also have the same spring kit in my SA and my RAMI and both of those have been completely flawless no malfunctions ever of any kind ever.