Took me a long time to read through every post. That being said.. Congrats on a nice buck. Glad you were able to get him down. The first shot was not exactly where you want it, but still would have killed him. Second shot was a little far back, but still would have killed the buck, third shot drilled him. Many are forgetting that at that distance, the bullet has really slowed down and isn't packing the walup that it would have at 200 yards.
Take bow hunting for example. The broadhead is not going very fast, but is intended to tear open vitals. In bow hunting, it can take a while for the animal to die due to the fact the hunter is not relying on kinetic energy from an expanding, fast bullet. They can die quickly with a bow as well, but tend to take longer.
Animals are tough and have to be to survive. And as others have said, bad shots are made and animals are lost at all distances.
im the most happy to see that you followed up your shots and made them count. Got the job done in the end. Good job.