I just got back from the range using the Crane O-ring AND a Wolff XP extractor spring on a 24" AR-15.
The shells were extracting well to the right of the rifle.

I had a buddy fire it a few times with me in another shooter's slot right next to the rifle. While I was messing around with my Vepr, he fired the AR-15 a few times and the shells were hitting my back. I watched closely and the shells would fly to the right and back but end up about 20' away from the original position of the rifle. I'd say that's some pretty strong extraction considering my AK does almost the same thing but much stronger and less "neatly".

I could understand why I was getting complaints about brass flying to the right with just the Wolff spring.

So if you're having extraction issues, a Wolff XP Spring will probably do the job and a Crane O-ring wouldn't hurt.

Just don't use the plumbing aisle O-ring because its made out of Buna-N/Nitrile which can't handle temperatures higher than 250F.

Actually, I've noticed that the plumbing o-rings work just fine. Of course, I've only bumped 5 consecutive mags through.

If that is the case, then I guess the extractor area doesn't see such high temperatures.

I only raised the concern because I've heard of people complaining their plumbing aisle o-rings melted/broke apart jamming up something else in the rifle (this is only what I've heard and read).

If anyone else has success stories using plumbing aisle o-rings in such applications as bump-firing fiestas or other high test situations, please post! :)