Ma Gui is famous for his short power wrist striking. He could easily break the arm of an attacker, at almost any angle. This is first trained as a long striking method, and gradually as the power is found, it does not need any distance to have power.
To practice the long power, sit in horse stance and alternate wrist strikes. Or, sit in horse stance feeling and either do single arm repeats or alternate wrist strikes. For a longer power, bring the assisting arm back behind the body. For a shorter power, keep the assisting arm in front.
To bring qi to the wrist, lightly hit the wrist into the palm of the other hand.