9threeXfifty7:
Great photos of the elk and your son. What a great experience and teaching him the truths that the past has a lot of truths that don't change.
Your son seems very proud of his take. Congratulations. 6.5X55 or 7x57 are great choices. I bought a 6.5x55 for my oldest son years ago. He later bought a Winchester 7mmWSSM. He actually hunts and shoots the old 6.5X55. He rarely takes the WSSM out.
I don't tell him "I told you so", because he already knows.