wacki, barrel length only adds 10-30 fps on your velocity from 20"-34", not much more power. What barrel length does do is extend your sighting plane and help with perceived lead. Dedicated trap guns usually have at least 30" barrels and many have 34" barrels. This length also helps you get a bit more weight out in front of you and helps with follow through of targets. Also the more weight of the gun the more it will help dampen recoil. Trap can be shot fine with an 18" barrel, but usually not as well as a longer one. As with any shotgun the fit to the shooter is the most important.