I have shot a coupledeer with these heads. Both deer were shot through the chest, I was happy with the way they performed (pass throughs and good blood). I don't believe that they stay in a full open position without pressure put on them. I suppose meat,fat or hair in the channel could keep them fully open.They are meant to slide, so I believe they just slid forward a bit after exiting. Wasthere any other issues, such aspenetrationor poor blood trail? You have to have confidence in your equipment. If there is some doubt,find a different head.