If it's spraying and the fletchings are covered with blood I'd say you poked through. Maybe you only got one lung or something because he shouldn't have gone more than 75-100 if you got both. It's possible you hit an artery, but even so, he should be down in a couple hundred yards given the time you gave him. I'd say with the arrow sign and the spray, he's done. That said, if it was at an angle like you say, it's possible you did as you suspect or maybe even slipped in behind the shoulder and out the bottom. I had one go 600 yards with his leg artery shot off, but he did die. You don't get spray from muscle wounds' There was VERY LITTLE blood on the ground even with his leg artery slit. He had a blood clot the size of a nerf football between the shoulder and the chest wall when I skinned him.