S'G' Extractor breaking

Don't know what is causing the extractor in my S'G' to break.

Happened 3 times so far. The lip that catches onto the case head is where it breaks off. Bolt is S' G' flat type.

Cleaned chamber as well as I can, wiping it dry before shooting. Recoil spring and guide rod in good shape, no kinks or peening. Gas piston functions properly. Trigger group works fine, have tried it in a couple other carbines with no problems.

Ammo is LC 71, Lot 50-205.

At a loss what else to look for, other than cleaning it again after 100 shots.

Any ideas ?

I have had a number of "commercial" extractors fail shortly after installing. Just wondering if these were USGI? Seems that the steel or heat treat may not be very good on some of those "commercial" items. Just a thought. Please let us know the answer when found. Good Luck...
Ed

Benchloader, who were the Mfg's of the three extractors that broke?
Did all three break using the same Ext. spring?
Does the chamber look rough or pitted?
Scott

Thanks for your input.

Don't see any markings on the extractors. Appear to be Type III though. Purchased them from CMP years ago with other spares, and also recently from Sarco. Didn't think to buy spare Extractor Plunger & Spring, been using same one, Type II.

Chamber looks fine to me, my light don't reveal anything unusual compared to my other carbines.

Swapped the flat bolt with a spare round bolt (OI) I have. Have to see how that works until another new extractor for the flat bolt arrives.