Center and Longsnapping techniques???

Long snappers and center's are two different animals. Each job is equaly tough. When teaching our C. I look at his arm length. For some I have them straight arm the ball back for others I make them have more of a bend. I want the ball to hit them at bottom of their sack if there was no QB under neath them.A drill I do is have the QBs or another C put the top hand underneath. Then I have the C snap the ball w/o a step if the ball hits the QBs top hand and falls staight down to the ground then it is a good sanp if not then adjustments need to be made. I think I got that drill from somebody on this message board (Bill Mountjoy?) or from Coach Tom Bass' book "How to play football the NFL way" Next I progress to the snap and step, then to the snap, step, and punch, lastly to the snap, step, and pass set. By the way, I love your site!