I got some lessons from Tony Marcino, and one trick that opened my eyes is to slide your grip hand forward,
to the front of the wrap. When you take practice swings, get very close to the CB (millimeters)
and when you're all the way forward, the back arm should be bent quite a bit at the elbow.
At this point, if you just use your arm and nothing else, you won't get much power.
Imagine your arm swinging and bending at the elbow as you deliver the cue.
Your arm power sort of maxes out when the forearm is straight up and down
at the moment you impact the cue ball.
If it makes contact after that point, when your elbow is fully bent, it's weaker.
So why do we start out with your elbow fully bent, if that's weaker?
Because if you put your body into it and lunge forward, pushing off your back foot,
your grip hand's shoulder and upper arm will come along for the ride.
At the moment of impact, they will be much further forward than they were
when you started. So now the elbow won't be fully bent anymore.
If you time your lunge and swing so that the stick contacts the ball at the moment
when your forearm is pointing roughly straight up and down at the floor... you're going
to get tons of force. That's the 'timing' thing people talk about in your break.
If you lunge and then swing early, the elbow is bent too much. If you swing late, it isn't bent enough.
This lunging motion allowed me to crack 23, but it does take practice.
You may feel like the tip is pulling back through your bridge too far or hitting the CB wildly
because there's so much extra motion in your break. But if you get a square hit just once you'll
be amazed at the difference, it's like an extra 5mph with hardly any strain.