WASHINGTON, March 8 (AP) — Hobbyists who build and launch high-powered model rockets could soon be subject to background checks, fingerprinting and storage inspections. Under new provisions set to go into effect May 24 under the Homeland Security Act, the Bureau of Alcohol, Tobacco, Firearms and Explosives would place further restrictions on the fuel that powers the rockets. Sport rocketry attracts thousands of hobbyists across the country. The rockets can stand taller than an adult, soar miles into the sky and are designed to land intact nearby. The new rules will require buyers of the rocket fuel ammonium perchlorate composite...