This is probably not the forum because this happened with factory ammo but other forums on the site don't seem to fit this post either.
After shooting about 350 rounds of the same lot # of 6mm ARC Hornady 108 ELD factory ammo, on the third round of the morning I felt a bit of extra recoil and this happened:
The bolt locked up and lucky for me there was a very nice guy shooting next to me that had all the tools. We put a rod down the barrel and he tapped on it while I hit the bolt hard with my hand and the case finally came out.
The action and bolt had no damage (Defiant Machine), but I didn't know if there was more damage and on top of that we could not find the primer and didn't know if there was.
My friend said "no problem" and produced a bore scope. After a through inspection, other than tiny loose bits of brass in the barrel there was no damage. And then we found the primer. It had gone in the magazine and then fallen to the ground when I removed the magazine to clear the rifle.
One in a million? I sure as hell hope so!