 A basic spreader choke is simply a "choke" with a larger diameter than the barrel; the spreader choke still makes the barrel more restrictive than just having a shorter barrel, but a shorter barrel may not be allowed due to legal restrictions.A number of recent spreader chokes, such as the Briley "Diffusion" line, actually use rifling in the choke to spin the shot slightly, creating a wider spread.The Briley Diffusion uses a 360 mm twist (1