A low-quality semi-automatic pistol, short-barreled (usually less than three inches) and easily concealed. Because they are small and inexpensive, Saturday Night Specials are especially popular with juvenile criminals. Federal law bans their importation into the US but allows domestic production and sales of these same weapons. Seven states have passed their own laws banning commercial sale of junk guns.
Saturday night special is a pejorative or slang term used in the United States for any inexpensive handgun. It is sometimes called an SNS in written shorthand. Traditionally, Saturday night specials have often been defined in some legal jurisdictions as compact, inexpensive handguns with a barrel length of under three inches (for pistols, overall length of under six inches) and low perceived quality, although there is no universal official definition of "Saturday night special" under any federal or state law http://www.bradycampaign.org/facts/faqs/?page=sns http://www.nraila.org/Issues/FactSheets/Read.aspx?ID=61.