Revenue Ruling 57-6

       A rifled bore pistol or revolver of the conventional type is
     not a firearm as defined in section 5848 of the Internal
     Revenue Code of 1954, but a smooth bore "pistol or revolver"
     is a firearm as so defined.
       Revenue Ruling 54-159, C.B. 1954-1, 251, revoked.

     Revenue Ruling 54-159, C.B. 1954-1, 251, holds that the
removal of the rifling from the barrel of .38 and .45 caliber
revolvers and the use of standard revolver cartridge casings, hand
loaded with shot, do not remove such weapons from the
classification of revolvers.
     The Internal Revenue Service has reconsidered, for
classification purposes under the National Firearms Act (chapter 53
of the Internal Revenue Code of 1954), the status of a pistol or
revolver, designed or redesigned to fire through a smooth bore,
primarily fixed ammunition consisting of the case, primer,
propellent charge and "shot" rather than fire, through a rifled
bore, fixed ammunition consisting of the case, primer, propellent
charge and a "bullet."  As a result of the comprehensive ballistics
and practical comparative tests, the weapons have been classified
as follows:
     A rifled bore pistol or revolver of the conventional type
meets the basic requirements of a "small projectile weapon" as
defined in sections 179.35 and 179.37 of the Regulations related to
Machine Guns and Certain Other Firearms, even if loaded with "shot"
cartridges for the reason that it is designed most proficiently
from a ballistics standpoint when discharging a "bullet." 
Accordingly, a rifled bore pistol or revolver of the conventional
type is not a firearm as defined in section 5848 of the Code.
     On the other hand, a smooth bore pistol or revolver fails to
meet the basic requirements of a "small projectile weapon" even
when loaded with "bullet cartridges" for the reason that the weapon
is designed to function most proficiently from a ballistics
standpoint when discharging "shot," equalling the potential of
shotguns with comparable specifications.  Therefore a smooth bore
handgun is not a "pistol or revolver" as defined in the regulatory
definitions referred to above and is not entitled to exception from
the provisions of chapter 53 of the Code.  Accordingly it is held
that such a weapon is a firearm as defined in section 5848(1) and
(5) of the Code and as such is subject to the provisions of the
National Firearms Act (chapter 53 of the Code).  
     Revenue Ruling 54-159, C.B. 1954-1, 251, is hereby revoked. 
However, under the authority of section 7805(b) of the Code, this
ruling will be applied without retroactive effect.