Doubtful, as any 8BA I have seen has the holes tapped right thru (no bottom) and the threads don't start until appox. 3/8" below the surface.Maybe some one posted this and I missed it. It looks to me like there wasn't enough thread on those bolts and they tightened up before clamping the main.
As mentioned they could have bottomed out also.
Two words : Three mains.

A pic of the fracture face will tell a lot.