Ground meat is not whole muscle finished cuts ground up; it is the trimmings from those cuts. The fat/lean ratio is determined some by the trimmings and some by adding lean or fat to adjust the ratio. Western steer beef is raised for its tenderness and has considerable fat, but that's what makes it tender. You mix those trimmings with extra lean beef garnered from local cow and bull meat (or imported, such as from Argentina or New Zealand) and derive the fat/lean ratio desired. In most packing plants, the trimmings are put in pallet sized buckets, then core samples are drilled through them in various spots and the samples go through a fat analyzer; that machine will tell the operator how much fat and/or lean to add to achieve the correct fat/lean ratio desired. Trimmings can be from all parts of the carcass, ergo the standardization of terminology that the ground meat does not come from a specific part of the carcass; rather, it is it's fat/lean ratio that matters; i.e. 73/27, 80/20, 90/10, 93/07. The best burger comes from the worst cuts, not the best cuts. Grinding up shank meat, neck meat, trimmings from the spinal column, plate and brisket trim, that's the stuff great ground meat comes from, lol! But, you don't have access to those cuts unless you butcher your own. You can add some shank slices from the meatcase if available and once in a while some retailers still offer sliced neck roasts or plate beef, especially in Jewish ethnic areas. The 'tube beef' many of you see in the meatcase (1lb, 3lb, and 5lb chubs of 73/27, 80/20, 90/10 and 93/07) is what comes from directly from packing plants and has the greatest flavor with the least waste possible; it is processed in 99.99% bacteria-free environment making a 45 day shelf life possible, and can be re-ground in your own grinder into sausages or meat mixes easily, plus great sliced up and pattied on the grill or in the pan. This is the only ground meat we use ourselves, buying the 5 lb. chubs exclusively, usually the 80/20. The meat ground in-store has a 1 day shelf life; the tube beef has a 45 day shelf life (from date of processing, usually 30-35 days in-store). The burger is usually a little coarser-ground than what you find in-store (you should see the size of the grinders they use, about 8 ft. tall and as big as a pingpong table, one cascading into the other to do a two-grind mix!); and you can always regrind it if you wish. I use it in all the snack sticks, summer sausages, etc. that I make, it's so much better, quicker, easier to use than to grind my own and comes from tougher cuts that have far more flavor than pot roasts (waaayyy too expensive to grind!). Cook the pot roasts as intended, they make much better pot roasts than they do burger!