That's exactly what the jerky gun does . . it looks like a caulking gun. You full it full of ground meat, put a tip on (there are a few . .. large flat, 2x small flat, round etc) squeeze the handle and it comes out in the shape of whatever tip you have on it.

I usually use mostly dry spices for ground meat. Put the meat in a mixing bowl (make sure the bowl is large enough to get your hands into) with your ingredients and mash it all up until it is well mixed (and dont forget a curing agent !).

Jeff