I found some very useful information in the following thread. I personally have been using the CCI 400 in .223, mild loads 23-23.5g IMR 4895 w/ 55g FMJ BTs, and have seen no indication of piercing in my auto feeder. I do plan on switching over to CCI 41s or BR4s when I use up my last 2000 CCI 400s. I figure once you know to avoid a potential problem, you should take positive action to do so. My choice is to avoid going higher on the load for now and switch over. YMMV
http://thefiringline.com/forums/showthread.php?t=505098