An interpretation by the Bureau of Alcohol, Tobacco, Firearms and Explosives that pistol grip shotguns are not shotguns has created an unforeseen legal liability for owners of such firearms. ATF’s Nov. 2009 FFL Newsletter declared:
Certain commercially produced firearms do not fall within the definition of shotgun under the GCA even though they utilize a shotgun shell for ammunition. For example, firearms that come equipped with a pistol grip in place of the buttstock are not shotguns as defined by the GCA.
Here’s another wrinkle, from Mike Vanderboegh at Sipsey Street Irregulars:
An October 27, 2010, letter from the Firearms Technology Branch ruled that such a firearm, with a 17″ barrel and 26-1/4″ overall length, was not subject to the National Firearms Act.
Read the rest of the article: http://www.examiner.com/article/atf-position-on-pistol-grip-shotguns-creates-new-danger