Bullets are a funny thing. And never expect them to do the expected for the most part. Why it did not expand (you had a pencil shaped wound through the deer?) is hard to guess. It just might have passed through so fast that ... well I don't know. I would have thought it should have expanded. I have seen roundball expand at that distance.

Was the internal damage the same size? No wound channel? At least you got the deer. And from all I have read, that is a great bullet.