The Sputter Gun, lacking any trigger, was designed to fire multiple rounds automatically, upon release of the bolt from its safety slot, until all ammunition was expended from the magazine.

In 1983, the ATF became aware that, William M. York, doing business as York Arms Co., was offering for sale a version of a Mk.II Sten that was capable of fully automatic fire that did not meet the Federal definition as a machine gun.

York advertised the “Sputter Gun” (so named by his attorney friend Ron Boutwell) as a firearm for those "who want the fun and excitement of owning and firing a fully automatic firearm without the government tax and red tape."

A then employee, Chuck Lanum, of the ATF Firearms Technology Branch (FTB) in Wash. D.C. made a scheduled personal visit to the York Arms Co. in Hurricane, Utah, to inspect and discuss some of the Sten-based firearms the company was manufacturing under their Class 2 FFL issued by the ATF.

[2]In spite of assertions by ATF or others this legal definition has never been changed by any Ruling or Congress and still stands as Federal law.