Hey man I can teach you how to Gatling. Its the cool thing to do. Start off by pressing the A button, then the B button, and then the C button. Take it nice and slow. I have confidence you can master this technique.
Also take a look at your action relvolver table at the link I provided. It will tell you the order in which you can Gatling / Action Relvolver / Normal Cancel / Magic Series / Order of hitting buttons.
http://www.dustloop.com/guides/bbcs2/frameData/tager.html