Revenue Ruling 57-34

       A barrel extension, having a diameter of four inches, an
     overall length of 16 inches, and no baffle plates, for a
     standard industrial gun produced by a domestic manufacturer,
     but which neither silences nor appreciably diminishes the
     explosive report of the gun, is not a "muffler or silencer"
     within the purview of the National Firearms Act.
       Any similar device, designed for use with an industrial gun,
     should be submitted for classification purposes prior to
     general production thereof.

     Advice has been requested whether a barrel extension designed
to reduce the risk of injury to the hearing of operators of
industrial guns is a muffler or silencer within the purview of the
National Firearms Act (chapter 53 of the Internal Revenue Code) and
the Federal Firearms Act, title 15, U.S.C., chapter 18.

     The Internal Revenue Service has examined the brochures,
plans, and specifications relating to a particular barrel
extension, having a diameter of four inches, an overall length of
16 inches, and no baffle plates, designed for use with a standard
industrial gun of a domestic manufacturer, and has witnessed
demonstrations of the device.   The stated purpose of the device is
to reduce the risk of injury to the hearing of operators of
industrial guns by projecting the report of discharge of the
explosive away from such operator.

     Section 5848 of the Internal Revenue Code of 1954 includes as
a part of the definition of a firearm a "muffle or silencer for any
firearm," whether or not such firearms is included within the
definition of firearm as contained therein.  Pursuant thereto,
section 179.31 of the Regulations relating to Machine Guns and
Certain other Firearms defines a "muffler" or "silencer" as any
device for silencing or diminishing the report of any portable
weapon, such as a rifle, carbine, pistol, revolver, machine gun,
submachine gun, shotgun, fowling piece, or other device from which
a shot, bullet, or projectile may be discharged by an explosive. 
Similarly, section 1 of the Federal Firearms Act, 15 U.S.C. 901,
includes in the definition of a firearm a "firearm muffler or
firearm silencer."

     The demonstration of the device described above conclusively
established that it neither silenced nor appreciably diminished the
explosive report.  Therefore it is held that this barrel extension
for industrial guns, conforming to the plans and specifications
examined, is not a "muffler or silencer" within the purview of the
national Firearms Act, chapter 53 of the Internal Revenue Code of
1954, or within the purview of the Federal Firearms Act, title 15
U.S.C., chapter 18.

     Any device of a similar nature designed for attachment to an
industrial gun, for purposes of affecting the report of discharge
in any way, should be submitted for testing so that a determination
may be made in each case whether the particular device is a
"muffler" or "silencer" under these statutes.   Similarly, any
person proposing to produce devices of this nature should contact
the Director, Alcohol and Tobacco Tax Division, Internal Revenue
Service, Washington 25, D.C.