Originally Posted by Supertac916
I could be wrong, but once you put the magazine back together and you put it in your gun it's illegal.
Two steps here.
If you get a parts kit after 2000, and re-assemble it inside CA as a 11+ magazine, that
part is a crime.
Using it thereafter is not, just as using a legally obtained 11+ mag is legal (e.g. retired LEO or had in state prior to 2000).