Most modern, high-poundage crossbows will blow themselves apart if they're dry-fired. There are reports all over the 'net. Check out ArcheryTalk forums.
BTW, if you're looking for a crossbow, don't try any of the Horton or Scorpyd models with the reverse limbs UNLESS YOU'RE PREPARED TO SPEND THE MONEY because once you use one of them, all the rest feel like garbage, in terms of balance/weight distribution.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.