Maybe I'm just not fast enough, but I've never had 360A become techable. 360B though, you do have to wait a slight moment, and it will be techable if you do it as soon as they hit the ground. the way I do it is to start the 360 at either the 1, 2, or 3 position. Then you can use the whole holding the direction down for x frames (5? I should probably learn that). Right when Tager crouches, I hit B. If they sit there and block, it'll hit and be untechable.