After years of experimenting we have what we (and a lot of customers) consider to be the best venison hamburger mix.
Take the weight of your venison and add 25% of the weight in pork butt and 12 &1/2% in Ground Chuck. Grind it twice through an 1/8" plate.
No, a food processor will not work. You would end up with a mushy mess of meat.
Dave