Baloney, or bologna, is a meat emulsion - a stable puree of protein, fat, and water with a completely uniform color and texture. Here, lean meat is pretty much pulverized to extract as much myosin as possible (myosin is the protein that encases fat particles, keeping the fat from leaking out of a sausage product).
At OP, we use an industrial bowl chopper to first grind up the lean meat, developing the myosin, and then we chop in the fat. It's similar to making mayonnaise in a food processor, where you start with the egg yolk and dribble in the oil to make an emulsion.
Fortunately, you don't need a commercial chopper the size of a Honda to make great mortadella or baloney or weisswurst. Many books will tell you to use a food processor to make emulsified meats at home. However, I prefer to run the meat through a motorized grinder over and over again, as I find that using a food processor can result in a complete mess and a terrible texture because you can only process 1/2 pound at once and the food processor whips air into the meat. I'm not saying you can't use a hand grinder, but you may end up with a less-than-perfect grind, along with huge forearms...
Taste our mortadella and you'll catch my drift. It's silk smooth, supper fatty and full of flavor - ready for your sandwich, to be cubed into an aperitivo or even made into a spuma.
*adapted from the Olympia Provisions Cookbook, written by Elias Cairo and Meredith Erickson