[Nnobby45]

Improper extractor tension, or broken extractor if it isn't pulling it out of the chamber reliably. The new generation P226's have an external extractor which provides easy access so you can change it out with a little training. Early generation with internal extractors are more involved. Or send the gun back.

Note: Some old models with internal extractors don't get cleaned inside the extractor tunnel (no access),and carbon can build up inside between the extractor and the breach block insert so it can't flex. You can try soaking the whole slide (not the sights) in solvent over night and blow it out good with canned air.

Broken extractors I've seen usually break so that they won't extract at all. Since yours is random and it usually extracts, I'd suspect tension. Solution is probably a new extractor if it's a new generation.

Easy enough to determine:

With the slide off the gun and barrel removed, you can insert a round up under the extractor and see if it stays there when you shake the slide a little bit, and rotate it. It will likely be too loose. Also inspect the extractor to see if the hook is damaged.