Pictures help, it is hard enough to diagnose a problem when the gun is in hand. A lot of new ARs have sharp edges and corners on the locking lugs and will shave off small bits of brass as the case is extracted from the chamber. This usually doesn't create any problems, and should lessen as the gun wears in and the sharp edges dull. If they are larger then very fine shavings it is likely that something else is going on. If you can get some pics on here of the shavings in the gun, and of the cases so we can see it also.
What kind of jam are you experiencing? Failure to extract the case from the chamber, failure to eject the case from the gun, or failure to feed a new case into the chamber? These all have different causes, and would help a great deal in figuring out what is going on.