I had 2 break in half after hitting the shoulder "bone" in my 3D target.
I thought it hit the metal?
Both hit were low the shoulder, where the rod is. I suspect the rod was the culprit,
Although I have not used them on game yet, I have shot them quite a bit this year. They are very accurate, and very sharp. The blades on the heads I bought are almost twice as thick as a muzzy, but IMO sharper out of the pack.
And yes, you can shoot a four bladed head with a three fletched arrow. I always make sure that the blades are lined up so they come off the bow the same way. But others have said that doesn't really matter. Can't hurt though.
I may give them the cast iron test sometime.