I have given the study a good once over, and here are the parts that stand out:
"Therefore, we recognized that any shotgun with one or more of these features represent a “type” of firearm that is not “generally recognized as particularly suitable or readily adaptable to sporting purposes” and may not be imported under section 925"
(1) Folding, telescoping or collapsible stock.
(2) Bayonet Lug.
(3) Flash Suppressor.
(4) Magazine over 5 rounds, or a Drum Magazine.
"However, the working group determined that magazines capable of holding large amounts of ammunition, regardless of type, are particularly designed and most suitable for military and law enforcement applications. The majority of state hunting laws restrict shotguns to no more than 5 rounds."
(5) Grenade Launcher Mount.
(6) Integrated Rail Systems.
This refers to a mounting rail system for small arms upon which firearm accessories and features may be attached. This includes scopes, sights, and other features, but may also include accessories or features with no sporting purpose, including flashlights, foregrips, and bipods. Rails on the sides and underside of shotguns—including any accessory mount—facilitate installation of certain features lacking any sporting purpose.
(7) Light Enhancing Devices.
(8) Excessive Weight.
Sporting shotguns, 12 gauge and smaller, are lightweight (generally less than 10 pounds fully assembled),
(9) Excessive Bulk.
Sporting shotguns are generally no more than 3 inches in width or more than 4 inches in depth.
(10) Forward Pistol Grip or Other Protruding Part Designed or Used for Gripping the Shotgun with the Shooter’s Extended Hand
"Therefore, it is the recommendation of the working group that shotguns with any of the characteristics or features listed above not be authorized for importation."
Of Interest as well:"The fact that a firearm or feature was initially designed for military or tactical applications, including offensive or defensive combat, may indicate that it is not a sporting firearm."
"examined numerous shotguns with diverse features in an effort to determine whether any particular firearm was particularly suitable for or readily adaptable to those sports. In coming to a determination, the working group recognized that a shotgun cannot be classified as sporting merely because it may be used for a sporting purpose."
"At the present time, the working group continues to believe that the activity known as “plinking” is not a generally recognized sporting purpose."
So, this is the study, the recommends for findings and regulations. There will be something coming out soon stopping the importation of fun shotguns.