Okay, so if I weigh 4 ounces of ground beef (22 grams of protein), do I go with that number instead of the 3 ounces it becomes (~15g protein)?
Yes, so long as the nutrition fact you looked up is for RAW. It will almost always say “cooked” if it is for weight after cooking.
Some people don’t get this and that’s why you’ll see someone online claiming they’re getting 30g of protein from their 100g of chicken breast. Here’s a good rule of thumb: if your 4oz/100g serving is over 25g of protein, something is definitely wrong.
With fatty ground beef the fat calories could become a little bit more complicated if you throw away fat lost in the cooking process, but I don’t eat beef that much and haven’t cared enough to really look into this. Probably not something you really need to worry about unless you eat beef at every meal or are contest dieting.