Got my son set up for season. Have possible problem though. Were out shooting today and had him pass a couple bheads thru. He' s shootin 45 # out of an Impact extreme, w/ Rocket wolverines. Couldn' t see where heads were opening. He was shootin @ cardboard target w/ excelsior bale backing.Rubberbands were pushed back over the ridge on blades, indicating they opened.May target not have enough resistance, thus no blade marks. I don' t shoot them but see they are a bit more forgiving to slight form errors. He hits 5" circle out to 30 yds consistently( he won' t be going that extreme 20 max). Has anyone experienced this but had no problems on deer?Does it sound as though they aren' t opening due to lack of blade mark in cardboard?They open fairly easy by hand, I' m perplexed??!!!!! Thanx for any assistance or advice.

Twig they aren' t designed to perform in cardboard, or foam or anything like that........It' s the nature of the design. They need hair and flexible hide to get those tips swinging out and open. In the materials you mentioned the blade tips grab, and they will simply punch through .
You can' t in any way compare performance on live game to a sheet of cardboard. They will open everytime on an animal........never on cardboard.
I' ve been shooting Rocket expandables since 1997.

Kinda thought that may be case but was unsure. this eases my mind somewhat. thanks!!!