Recently I have started grinding my own beef to make hamburger patties. I've been using chuck roast with great success. I cut it up into 1" chunks and run in through my 3.5mm grinding plate twice. This has been producing amazingly tender burgers. Some of the best burgers I've ever had.
I am very happy for my success, but I don't really feel like my accomplishment is complete until I understand what makes them so great. These burgers are way more tender than the fresh ground meat I get from the meat counter at grocery stores. I even buy the stuff that hasn't been packaged or compressed... it is fresh out of their meat grinder. However I cannot begin to make burgers from their meat come close to how tender mine are.
Anyone have any ideas? I form the patties the same way in either case. The butcher showed me his grinding plate today and I wish I brought mine along to compare. It could be that they are using a finer grind and that is making the meat compact more easily. That is the only theory I can think of, unless adding meat trimmings is going to result in a tougher burger, because I know they do that too.