The whole point of what I wrote is that the bullet ISN'T going out of scope during the entity loop. It goes out of scope at some point before that, and the GC just happens to collect it sometimes during that loop, causing the crash. But you don't really know when the GC will collect something.
That's what I thought initially, but if that was the case, it shouldn't be in any lists by the time it's collected. Why is the mesh still in the MeshUpdateList after the TBullet which "owns" it has gone out of scope? Surely when the bullet goes out of scope it removes it's mesh from the MeshUpdateList?