What howlnmad said in his last two posts is correct.
Tungsten-carbide is brittle and can break if contacted too hard with the shell holder.
Originally Posted by howlnmad
The FCD will work fine for jacketed bullets. It's with lead that problems can arise.
The Crimping function of the die works fine for either lead or jacketed and gives no problems with either. It is the the post-sizing function (sizing AFTER the crimping) where problems arise. Crimping has nothing to do with this part. Problems can arise with jacketed, plated or lead, but are much more common with lead. Less common with plated and rare with jacketed.
balderclev, are you using a single stage press?