Go to your local store, buy a potato, and stuff it at the end of the barrel.
However, don't forget to register the potato first at your local BATF office, fill out all the necessary paperwork, and wait for your permit to arrive.
If the wait is too long, then I suggest peel your potato, cut it into pieces, and you have a nice healthy snack of french fries 100% recommended by the American Heart Association. You may not have a "functional muzzle brake", but at least you're not hungry anymore.