I made a video just for this question
Nice video, plouffe. Concise and easy to watch. I run the G21 with factory* G20 6" barrel, Wolff 22# spring and rod, factory G21 extractor. No extractor problems so far that I recall but I'll keep an eye on that.
* Actually, my smith cut and ported the barrel (attached). Of course, I could have bought a ported Bar-Sto 10mm barrel but this barrel is mine!