The H&R Handy-Gun is not just a "sawed-off with a pistol grip". It is a smooth bore shot pistol manufactured from the early 1920s to 1934 by the Harrington and Richardson Arms Co. It was a small game gun available in .410 bore and 28 gauge with an 8" or 12-1/4" and other calibers were rumored to exist. A company rep was quoted in 1985 as stating that "over 25,000" were made. Manufacture was stopped in 1934 with the passage of the infamous National Firearms Act - presumably passed to get Thompson submachine guns off the market because they were the favorite weapon of the bootleggers - never mind that prohibition was repealed the year before (1933).
It was never clear why the Handy-Gun was on that list from the beginning since it was a single shot .410 pistol chambered only for 2-1/2" shells and would never be a weapon of choice for defense, offense, or bank robbing or any such activities. It is even less clear why the BATF/ATFE has consistantly refused to remove this gun from the NFA list although they did reclassify it as a "CURIO & RELIC" some years ago.
I acquired mine as a gift from one of my dad's friends in 1934 since he knew of my interest in gun collecting - it was a birthday gift for my 8th birthday. It is duly registered and has always been. There was a period of "amnesty" for the month of October, 1968, for those owners who had specimens not registered to register their guns.
As far as I know, there is no way one of these can be legally registered now and the fine for possession of an unregistered Handy-Gun is $10,000!!
Eric Larsen published a small booklet on this gun in 1993 (Library of Congress Catalog Card Number 93-91518). At that time, he had located some 165 or so specimens and I called him to report mine. He had, by that time, located about 225 guns including mine.
I lived in a very remote rural part of western Nebraska at that time and I shot my share of rabbits and prairie dogs and even a few pheasants that I got close enough to get. The effective range was only about 15 - 20 yards so most pheasants were pretty safe.
I have heard of a couple of specimens for sale over the years but they were unregistered and, under the current regulations, there seems to be no legal way one could purchase one of these guns. In view of that, I suspect there are a good many of them around and there is no way of estimating what that number is.
Mr. Larsen and others have tried over the years to get the Handy-Gun removed from the list but, the ATFE, in all its bureaucratic wisdom, has always blocked these efforts. It is a real shame because it is only a collector's item and not a threat to society by any stretch of the imagination.