I had the same problem of deflecting off the ribs a few years back when I shot a doe at a steep quartering angle, fortunately the arrow did penetrate the chest cavity but didnt do it until just in front of the heart. The arrow entered at the last rib, and luckily all the arteries coming out the front of the heart got cut when she took off runing with the arow still in her. That was a 100grain 3 blade muzzy.