After experimenting for several years back in the 70's I developed a formula that we use to this day. It's so good that several of our customers will have all their trim made into hamburger and not our specialties! (Darn it.)
    Take the weight of your venison add 25% pork butt and 12.5% Ground Chuck.
     i.e. 20# venison, 5# pork, 2.5# beef. Grind twice through an 1/8" fine plate.
   This is one I will guarantee is great.

Dave & Ruth