A number of criteria were used to come up with this number, including gun registration numbers, expert estimates, household surveys, proxy indicators such as GDP and gun suicides, and comparison with similar countries. But even they have admitted that there are no easy rules to rely on, and that “social science, with its emphasis on verifiable indexes, naturally leads to undercounting total civilian arsenals.” Each of the five criteria listed has problems, potentially huge problems. There is no mandatory gun registration in the United States. Their expert estimates have differed by as much as a factor of ten for some countries, even modern Western countries such as Switzerland. Household surveys tend to be less reliable the more sensitive the subject, of which gun ownership certainly is one. Some people will just not readily give out that information. We’ve just witnessed what happened in one state. Even under the threat of a felony charge, it is estimated that the compliance rate for gun registration in Connecticut is less than four percent.In 2009, the Congressional Research Service estimated that the number of civilian firearms in the United States at 310: 114 million handguns, 110 million rifles, and 86 million shotguns. If correct, the current estimate woefully undercounts the number of firearms.
Even figures as to firearms sales undercount because not all firearms sales go through NICS--some states have their own systems and, in those states, no background check is required for persons holding valid Concealed Carry Licenses. I would also note the millions of parts kits imported into the United States over the last 10 years--how many of those were built into firearms using owner made receivers, thus not being included in the manufacturing statistics?
Griffen notes that industry sales figures may give a better indication. He observes:
There were over 47 million guns imported, manufactured, and sold between 2008 and 2012. Add another 15 million for 2013—a conservative guess based on what we know—and we’re well over 60 million new guns in the hands of gun owners since 2008. That means we have averaged over ten million new guns sold per year for the last six years alone.
... Around the time of the Clinton Assault Weapons Ban, there was a sharp increase in the number of domestic firearms manufactured, and total firearms sales were averaging seven to eight million per year. The end of the 1980’s also saw a large increase in the number of firearms produced domestically, with total gun sales averaging well over five million annually. ...Moreover, the number of new shooters is exploding:
According to a recently published study by Smith and Wesson, the number of new shooters is exploding. In fact, there has been an overall increase in the number of households owning guns in recent years, not less. Who is buying? 20% of shooters were new to shooting within the last five years, over half of them in 2012 alone. Two-thirds of new shooters are between the ages of 18 and 34, and women represent 37% of new shooters. According to Smith and Wesson’s survey, the top reason for gun ownership is personal safety/self-defense. That outranks hunting, recreation/sport, and target shooting combined.Getting back to the original question, however, Griffen writes that during the period of 1986 – 2012, over 164 million new firearms were manufactured or imported and sold in the United States. He thinks that if this was extended through 2014, the number would be 200 million. Accordingly, he figures that an estimate of current ownership of 350 million would be conservative. But even so, using that figure, by the end of 2016, there could be over 400 million firearms in the hands of Americans.