Interesting Colt 6920 failure.

Found this on a forum and I thought was interesting. Even Colts fail!

I attended a firearms training course (Magpul Dynamics Dynamic Carbine 1 & 2) for the first time in 15 years from November 6th through the 8th.

... That leads us to the most dramatic Gear failure of all. Once I had determined that I would need to move the ACOG on my SIG (and therefore would need to re-zero it) I decided that I would mount it on my much lighter Colt 6920. The SIG556 was heavier by nearly four pounds than the 6920, so I decide to give the Colt a go. I switched the ACOG to the Colt and got on the firing line. The drill was firing from the urban prone, weapon side position. We loaded and made ready and I waited for the threat command. When the threat command came I went into the urban prone position and fired. On the second round the upper receiver blew apart. It took a few seconds for me to get oriented and realize what had just happened. I checked to see that there wasn’t another round in the chamber and raised my hand to let Travis know there was a problem. Travis was already on the way as he said that he thought that I was on fire from all of the smoke that was rising from me. There was a medic who checked me out real good to ensure that some shrapnel hadn’t penetrated my skin anywhere without my being aware of it. I sustained only minor injuries (a bruise on the left forearm and some flash burn to the face). After the medic gave me the green light I went to my Pathfinder and got my SIG556 back out. I put the ACOG back on it and got back on the firing line.

The 6920 is on its way to Colt Manufacturing for analysis as of this posting. I will certainly post the results of the analysis as well as the resolution when that information is available. I would appreciate it if the wild guesses as to the cause of this failure were withheld until Colt Manufacturing has had a chance to check it out. I will give a few facts that will help to keep the conjecture to a minimum. The barrel was clear before and after the event and the ammo used was factory XM193. I don't know if the brass was ejected, it appeared to be, however, there could have been part of the brass case left in the chamber, I was too busy trying to get back to training to check, then the gun went via FEDEX to Colt before I had the chance to check because I was trying to catch up on all of the work I had neglected while out running and gunning.