The Helix not only shoots fast, but it also changes calibers quickly. My test sample came with barrels, bolt heads, and magazines for both .308 Win. and .223 Rem. Going from one caliber to the next takes less than a minute and requires no special tools. Pushing a button on the forend releases it so that it can be slid forward, exposing the lever that holds the barrel in place. Moving the lever 90 degrees frees the barrel. The barrel fits snuggly into the round recess in the receiver but wiggles out with minimal effort, even when the rifle is hot and dirty. Slide the new barrel into place—the bolt head is inserted into the barrel beforehand—throw the lever to tighten the works, clip the forend back on, and the rifle is ready to go.