Back from hunting smurfs...
My scythe got a real workout this weekend...
Smurfslayer comments on the above mentioned ammo failure.
I mentioned to His Tacticalness earlier that I suspected a case kaBOOM. If I were to guess - and that's all I can really do with everyone else here - I would say that H.T. suffered a case split & failure at the base and that the case material residue is what we're seeing in the chamber. Further range inspection with a surefire light revealed a light colored line that ran the length of the case in the chamber, which ran parallel with the chamber & barrel, looking as if the case "split" horizontally as well as the calamity at the "base".
IIRC, His Tacticalness indicated to me that he did not notice any "stickiness" in extracting the empties, so I'm not inclined to suspect an overpowered round, or overpressure - too much crimp, bullet setback, etc. I've seen the results of a revolver case split at the base before, resulting in a case "rim" which simply fell out with the remaining cases, but the actual length of the case still left in the chamber. As many of you know, or those who may visit my website to check for new goodies who have perused my 500 S&W page know, I've had cases split along the length of the cartridge... I think that the difference is that my split cases were way overpressure, whereas His Tacticalness are more indicative of a defective case at normal pressure, thus explaining the seemingly normal extraction.
Since you've got doc & pictures Your Tacticalness, I concur with the P.P. .40 bronze brush recommendation, and maybe a couple of pictures along the way. If this fails to dislodge the offending material ( I hope that's what it is, and not metal from the chamber that's been cut out ) then use a somewhat sharp piece of metal, like a paperclip to determine if you have excess, leftover case material, or, the chamber is bollixed. If the former, gently pick at it to see if you can break it loose - DON'T force it. If you have the latter, where the chamber is hosed - metal eaten or flame cut away, then that's a warranty issue, definitely. Is the rest of the chamber clear now?
If you're not comfortable going any further, don't! we can all take a look Friday to be sure. FWIW, I don't think I ever fired CCI's in any of my Taurii, but I have fired a couple of boxes through my 627/327 combo w/o incident. Only incident I've had w/ blazer is ( 1 IIRC ) a misfire, that went off on the 2nd strike.
The results of a similar failure in a semi-auto are usually not as pleasant. Particularly those which don't have fully supported chambers. Most of the mfgr's proof their guns with hideously over pressure rounds - Beretta uses 60 or 65k psi as I recall (saw cases of this ammo on the tour) - that's more pressure than a 500 generates. Of course, the gun only has to survive 1 shot or a few shots at that level...