Don't get me wrong, they ARE rare. Disregarding internet sources, I've only ever run into two people that said that they witnessed a KB "in the flesh" so to speak, and even in those two cases, I did not get enough detail from the witness to get a full picture of what actually transpired, although one of the two was an LE training environment, which basically indicates use of factory ammo. I'd put the odds of having a KB right around the realm of getting hit by lightning, or thereabouts.
To put things into perspective, There's an acquaintance of mine that does completely idiotic things with his G22, and hasn't managed to blow it up
yet. Shoots tons of lead through the factory barrel, uses max loads on it all the time, etc. Even he still hasn't managed to blow himself up -YET-.
![Laugh [laugh] [laugh]](/xen/styles/default/xenforo/smilies.vb/012.gif)
Obviously a sample of 1 isn't worth much.... but it does show that variables are often hard to track, and separating hype from reality is difficult.
ETA- Another reason why you might not hear KB reports firsthand, is a lot of times, if the person knows they did something stupid to cause it (eg, firing after a squib, or double charging a round) they might be less likely to report it, out of a matter of "pride" or ego or whatever. IMO this really isn't a loss stats wise, since "user induced" KBs really shouldn't be included. Almost any centerfire handgun can be blown up, just ask Clark Magnuson. (Although, I think he stated he was unable to blow up a .25 ACP, simply because the case was incapable of holding enough powder to do the job. )
-Mike