What do you add to a meatball mixture to ensure that they are dense?

I use half ground beef like chuck and half ground pork first I mix 1egg for each pound of meat with Panko bread crumbs, parmigian cheese, garlic,fresh parsley,salt,pepper and milk mix it all in a bowl then add the meat and mix till all combined shape into balls I like mine the size of a golf ball brown as you please on stove top or in oven

Julia Child's recipe calls for adding cooked rice. Adds a delicious texture and taste. She also includes sauteed onions and grated cheese. Really wonderful recipe.

Breadcrumbs and egg will help give you a fine, dense texture -- they won't be as "meaty" per se, but they'll hold together well.

Use lean ground beef and add panko accordingly to how much "wet" ingredients you put in (eg, egg).