Use your voice and keep the air moving slow and constant without a lot of velocity. Also try more backpressure. It will do it just fine once you figure it out. You can also tune it just a little harder to blow or deeper tone and that helps also. I like mine a little easier to blow to keep it fast, but tuned a bid deeper. If you want to try this you can move the wedge toward the reed tip just a bit off the quick tune studs and then don't set the guts quite so deep. It is a little tricky to get just right, but once you do it sounds good and it's fast, but you can still get the low tone with some added backpressure.
More ammo! I need to shoot something!