I have only gotten close to a Buffon's Macaw one time. The pet store I got Clifford my Scarlet from had a Buffon's there just before Clifford came in. His name was Eddie and he was HUGE, especially because he was only 9 months old. Buffons are a little lighter green than a Military but much larger in size. In South America they are called the Great Green Macaw. Your boy looks really young. We surely would like to hear all about him!
In these pictures Tucker is 9 and 10 months old. I will post more pictures sometime this weekend. At nine months Tucker weights 1400 grams. I expect that when he is fully grown he will weigh 1,700-2,000 grams. The buffons can get to be the same size as a Hy. I dont have a military but Tucker is a light flourescent green overall, red crest, blue and yellow under wings and tail (also some red under the tail). His feathers are gorgeous. You just don't see that vibrant colors many places.
My boy is a rough and tumble boy. He loves us all and regurgitates on myself, my adult son and my daughter-in-law (all bird lovers). He even puts up pretty good with my 8 year old daughter and 5 year old grandson! lol