In a very scientific experiment, I put it all in a little plastic bag then smacked the shyt out it several times on my concrete patio and still couldn't get it to break up completely. There are multiple chunks in there still bigger than a 00 buck pellet. I smacked it so much the pellets started coming through the bag.
Makes me wonder if it does break up completely every time when fired. However, I went back on some of my old pattern pictures and don't see any evidence of holes made by chunks. Looks like mostly individual pellet holes. Maybe a couple holes made by 2 pellets still stuck together.