Very amazing to go through both shoulders at 40 yards. I took pics for posts like this
that is a good double lung and you missed both of the large scuplas and the other big bones. that's why the arrow passed through.
When I read it went through both shoulders I automatically think bones. Just for the record I don't believe a spitefire will go through one scupla bone let alone two at 40 yards. Don't really care what ya shoot it out of either. It would take a picture of both bones with holes in them to prove it to me.
Last week i shot a doe at 10 yards with no passthrough and didnt get her.
I would suspect that you did hit hit scupla bones on this one,which is why you could not find it..
So to answear the question if you stay away form the big sholder bones and you have enough kentic energy and good shot placement the spitefire will work. I don't use them anymore, because I can get the same results from a smaller head, shockwave being one of them. good luck...