Hitting through the ball analogy: Pistol vs Rifle. This is an analogy a coach used to teach me the contact phase of the groundstroke that Vince Spadea is discussing in a video clip in another thread. He explained it by talking about the rifling in a gun barrel. When a bullet is travelling down a rifle barrel it has a longer distance where it's being guided by the rifling. After going through that longer distance and being guided forward it really picks up more speed and power and spin. In a pistol, it's not as accurate or powerful, because their is less distance forward and rifling over which to control the bullet and add power and spin. Now if you look at the physics of a tennis groundstroke, this analogy isn't even true. because the dwell time of the ball on the strings is so short, during a lot of the time where you're hitting through your contact zone and getting that power forward the ball isn't even on the strings. But it's a visualization technique to teach the student to have a long contact zone and follow through, which will create power, control, and spin. I'm not familiar with guns, that part of the analogy might not be true either from a physics perspective. It's a visualization technique to teach students firm clean contact, a long consistent contact zone, and a long follow through. If a student has these fundamentals, they will be learning the basics, and develop consistent spin, power and control.