NOW FIRST: I HAVE NOT USED THEM SPECIFICALLY,BUT AND THIS IS A BIG BUT: we've retro-fitted carbon inside alum. shafts, and made them pretty precise (this all at the local shop I work at every once and a while)....my experience with this type of construction is that the shaft still bends. I think what the FMJ is going for is the punch of aluminum + easy arrow removal + stiffness of carbon. The easton A/C/C shafts are what they should have just stuck with I believe. When you have carbon shell the alum. interior won't generally bend, now, if it's bad enough they will, but they are pretty resilient. When the alum. is on the outside it seems they bend much easier. ONCE AGAIN THIS IS ALL SPECULATION AS TO WHAT MAY HAPPEN WITH THE FMJ'S NOT NECESSARILY WHAT WILL HAPPEN. *just had to put that disclaimer on there*