RE: Can you help me figure this out?
 

" Most mechanicals open...." Maybe! However, fixed and replaceable heads always open. :)

Based on reports by some .... reaching many, mechanicals do not open all the time, have penetration problems, and are often and greatly affected by angle of impact.

Since it is the broadhead that kills; not the shaft, nor the speed of the bow, or the latest sight or rest, I just cannot accept that it is reasonable to gamble with the only thing that will make the kill just because the heads act like fieldpoints. It appears they do. All the way into and through the deer.

In my book, " Most mechanicals open" just is not good enough.

RE: Can you help me figure this out?
 

Not in this case. Reason being, it wasn' t your ordinary o-ring. It was a flat band type that if it rolled, probably have twisted and not remained flat. Plus, there was no indication in the mud on the head. It would have scraped away the mud on it' s path back down the head. And when he opened it up manually, there was no mud on the leading edges of the blades. They were as clean as the day he put them on the arrow as the leading edge is protected by grooves in the ferrel.