15 CFR § 272.3 - Approved markings.
The following markings are approved by the Secretary of Commerce:
(a) A blaze orange (Fed-Std-595B 12199) or orange color brighter than that specified by the federal standard color number, solid plug permanently affixed to the muzzle end of the barrel as an integral part of the entire device and recessed no more than 6 millimeters from the muzzle end of the barrel.
(b) A blaze orange (Fed-Std-595B 12199) or orange color brighter than that specified by the Federal Standard color number, marking permanently affixed to the exterior surface of the barrel, covering the circumference of the barrel from the muzzle end for a depth of at least 6 millimeters.
(c) Construction of the device entirely of transparent or translucent materials which permits unmistakable observation of the device's complete contents.
(d) Coloration of the entire exterior surface of the device in white, bright red, bright orange, bright yellow, bright green, bright blue, bright pink, or bright purple, either singly or as the predominant color in combination with other colors in any pattern.
(e) This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of Federal Standard 595B, December 1989, color number 12199 (Fed-Std-595B 12199), may be obtained from the General Services Administration at General Services Administration, Federal Acquisition Service, FAS Office of General Supplies and Services, Engineering and Cataloging Division (QSDEC) Arlington, VA 22202 or at the General Services Administration Web site at: http://apps.fas.gsa.gov/pub/fedspecs/. A copy may be inspected in the Office of the Chief Counsel for NIST, National Institute of Standards and Technology, Telephone: (301) 975-2803 or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.