I think the powder charge sounds about right. You hit a shoulder, that thing will really open up. No telling how far it will penetrate, but you're going to get expansion. I think instead I would try to tuck it behind the shoulder and angle it towards the outside shoulder. Then you should really make a mess of the internal organs and still knock the deer a good jolt..

I actually like those cheap shots. I would not hesitate to shoot a deer with one of them.