In order to reach your deepest layers of your muscle and speed up your growth and recovery, you'll need a unique tool with enough pinpointed pressure on one hand and yet soft on the other so you won't hurt yourself.
After every workout your muscles gets a bit contracted (even if you don't feel it), it's kind a like having a rubber on a hose, it stops the blood from reaching to the muscle. Now there's not enough blood reaching your muscle, which means not enough oxygen, which means your muscle can't grow or recover. The solution is to break those knots (get rid of the "rubber") in order to exploit the full potential of your growth and recovery. The massage gun is the best available solution, as you don't need to go see a deep tissue massage therapist after every workout and yet the results are equal (and some say even better).