I have used some. The ones headstamped "RP" are quite good - no primer pocket crimp and have had no significant issues with brittleness. Primers seat more easily than with Federal brass. The "CJ" stamped brass need to have the primer pockets swaged or reamed but seem OK once this is done. I don't use them when trying for precision, mainly for plinking rounds but from the results they may not be much better or worse than Winchester or other brass.