Create two different inner diameter with an inner barrel, because airflow forward faster than BB,before the BB is not out of the inner barrel, there has to be part of the gas out of the inner barrel, the main purpose is to let the BB rear end of the high-pressure gas, in part relatively large diameter can completely cover a BB, when BB ejected, achieve "front guide" function,
more stable flight trajectory starting point, still more straight to the target !!
Of course, use 『T-N.T. Air-cushion Directional Inner Barrel』with『T-N.T. Located Directional Rubber』to get the better efficiency !!