TCScout,
I am just going to read this post and not give MHO as Gary has this totally under control.
What I will humbly mention in the meantime though is:
Obvious Factors:
1. Range
2. Shooter ability
3. Shooter experience (not the same) (Exciteable as in ELK FEVER?) I still get that sometimes!
4. Shot placement
5. Bullet construction and design
6. Angle of bullet impact to animal
We all know a .22 will kill an elk; that aside, I bow out.
Thank you for listening.
Gregg
PS: I was unable to get the photo of your son with his deer to come up.
PPS: TC Scout, No matter how the other opinions play out, I applaud you for your times hunting with your son. I agree: it is the best!!!