Action Army Ares Striker AS01 barrel spacer set Want to stabilise your inner barrel a bit more? Try these! When you fire an airsoft rifle, there is an element of 'barrel flex' involved which can be very very small or particularly noticeable if the inner barrel or other parts of the barrel assembly are loose. There are expensive ways to solve this and very low cost ways. This is one of the lowest cost and easiest methods as it tightly secures your inner barrel inside the outer barrel and is fitted with rubber o-rings to help absorb and vibrations that may otherwise effect the rifle accuracy.