Casting is a strange beast

So, I'm taking a glass casting class, and for my third piece, we had to do a found object. I did a toy revolver. It casted great! Except for the chamber. I don't know how it managed to do it, but it left out the entire chamber and trigger. My guess was the mold was so long, the glass started to cool before it filled the whole thing. Here's some pictures.

Ah well. It's a pretty cool looking error either way. Sometimes the glass just doesn't want to do what you want it to.