@ Nirogen
Only had my crossbow for a year and only purchased items manufacture recommend. Playing it safe until someone I trust gives me the lowdown for crossbowing.
Diablo bolts are the only one's i've used so far.
When you say 30% failure rate when using these bolts. Are you talking about in general(target practice) or after the kill?
After the kill. Actually 40%. Out of 5 deer killed the bolt shattered on 2 of them, 2 recovered intact and one bolt lost. All cross body boiler room shots with no large bone impact (just ribs). My guess is it's just too much kinetic energy for the bolt to handle - kinda like when a bullet fails to penetrate because it is going too fast and instead blows up on impact. My solution has been to switch to a stiffer stronger bolt - kinda like switching from an SST to a partition if comparing to bullets.
Like Stx suggested join the excal forum and post there. There are a lot of crossbow gurus on that site who actually know what they are talking about. In particular pay attention to anything posted by "Boo" and/or "Big John."