I am an armpit shooter. I aim to put the bullet in the lungs, but only just above the heart
I guess I do not see a lot of difference with shoulder(s) hit or just behind. I would hate to say more run off a short ways with one over the other. I will say though that even with a decent hit though just a tad back I have had to chase deer too far. A shoulder shot can deflect and miss vitals and then you have a three legged run off that can be very hard to catch up with.
I prefer three quarters to or away so I can run the bullet just above the heart and get both lungs too without touching shoulders, but you don't always get that.
If I cannot put the bullet close enough to the heart to rupture it I tend to keep it as high as a high shoulder shot and forward so I get the big vessels and it bleeds out almost as fast. When hit there, they often will do the sag/knees buckle and go down in place. That looks a lot different than the flop that come with the high shoulder hit. I only use a high shoulder when I have to be sure it goes down in place and stays there, I don't like losing the meat.
