Posting some information that may be helpful to those who own M60s and experience this failure.... We currently have an M60 in on repair with this exact issue, so I took some photos and video going over the work as we did it... This should help understand why this happens and just how in depth the repair is.
Aaron - Mohnton, Pa
Sales@BeltFeds.Com
A nice M60e6... Customer was shooting and the bolt locked solid in the chamber. We were able to see that the round had been expended and the cartridge was empty:
The first step we take to free this up is shown in the video below from our YouTube channel. In this specific case, it was ineffective and the bolt did not budge even a hair.. It should be noted, that you should ensure there is not a live round in the gun when you are doing this.
After exhausting our efforts, we determine that the only course of action to free this up is to cut the bolt in half. This is complicated to do while the bolt is in the receiver. These heat treated bolts just kill end mills.
We cut this in a specific way that prevents any damaging from occurring to the operating rod:
Once the bolt is complete cut in two, we are able to pull the barrel out of the front.
The most common cause of this is extractors getting blown out of their pocket, which prevents the bolt from camming out.... We can see here that this was the case for this gun. NOTHING would have gotten this free. When the bolt is fully seated in the chamber the extractor is facing down so it is completely inaccessible.
The culprit.... Lake City 08 (I still think it may be a reload) ... You can see the back end of the casing is blown out.
Below is a video going over the removal of this bolt and the casing. In this specific instance, the casing didn't full seat. It appears as though it bulged at the bottom preventing it from doing so (possibly a reloaded round that was resized and messed up?). The caseing blasted out of the rear side which in turn blew the extractor out of the bolt.
Here is another video of a repair we did with the same issue. Just for a different view point etc: