Around three out of every four detachable magazines sold over the last 30 years have been capable of holding more than 10 rounds of ammunition.

That’s according to the Detachable Magazine Report released by the National Shooting Sports Foundation (NSSF), an industry trade group, on Friday. It estimated 963.7 million rifle and pistol magazines entered the commercial market between 1990 and 2021. 717.9 million of those magazines, or 74 percent, can hold 11 or more rounds.

The report provides fresh insight into just how popular so-called large capacity magazines—typically defined by states that ban them as those capable of holding more than ten rounds—have become among American gun owners. It suggests they remain highly sought after despite the political controversy surrounding them. The report’s findings are also likely to factor into ongoing lawsuits challenging state magazine bans, as gun-rights advocates continue to argue magazines with a capacity of 11 or more rounds are “in common use” for lawful purposes–a standard the Supreme Court has used to strike down handgun bans.

Larry Keane, NSSF’s General Counsel, argued the report confirms as much.

“The data establishes that law-abiding gun owners overwhelming choose magazines that can to hold more than ten rounds for lawful purposes including self-defense, target shooting and hunting,” he said in a press release unveiling the study.

To develop its estimates, the NSSF looked at the ATF’s Annual Firearms Manufacturers Export Reports (AFMER) to identify the number of rifles and pistols produced by each manufacturer over the study period. It filtered out makes and models of firearms that do not accept detachable magazines, such as revolvers or fixed magazine hunting rifles. The group then surveyed the resulting list of manufacturers to determine how many magazines they provide with each firearm and how many they made available to the commercial market through wholesalers, retailers, and direct consumer sales. It excluded military and law enforcement sales.

“If historical information was not available, a value of one magazine per pistol and rifle was used for the list of top manufacturers,” the report said. “Consumer market totals were taken directly from participating magazine manufacturers with no adjustment. Totals of each segment were rounded to the closest thousand.”

The report estimates that 29 percent of the magazines were provided “in the box” with each newly manufactured firearm. Manufacturers sold the remaining 71 percent of magazines directly to the consumer market.

According to the report, rifle magazines were the most commonly sold detachable magazines over the period studied. Rifle magazines capable of holding 30 or more rounds, such as those that come standard with AR-15s and similar rifles, represented roughly 46 percent of the total magazines. The report also found that the aftermarket supply of those magazines was thirty times larger than that for rifle magazines holding ten rounds or fewer.

For pistols, the report identified over 209 million magazines capable of holding 11 or more rounds, compared with just under 175 million capable of holding ten rounds or fewer. The NSSF attributed pistol magazines’ more even capacity distribution to the recent popularity of compact carry handguns.

“The popularity of small ‘conceal carry’ pistols highly influenced the distribution of pistol magazines in most recent years, but following trends in manufacturing, many of these pistols are being updated with higher capacity magazines as designs are updated,” the report reads.

The report adds some quantifiable data to the existing body of research surrounding the popularity of so-called large-capacity magazines. Other estimates have relied primarily on survey responses from gun owners. The 2021 National Firearms Survey, for instance, previously found that around 39 million individuals have owned up to 542 million magazines that hold over ten rounds based on a sample of nearly 17,000 gun owners.

However, the NSSF approach is not without its limitations. The group acknowledged that not all of its estimated magazine totals are actually owned by American gun owners since its data encompasses all magazines made available for public sale, whether or not a customer purchased them. The study also did not account for broken or discarded magazines due to a lack of available data. As a result, the total estimate could potentially overstate how many magazines are actually in private collections.

At the same time, the group noted methodological limitations that could potentially lead to an undercount of civilian magazine ownership. The exclusion of shotgun magazines from the study and magazines produced before 1990 were some examples of magazines missed by the report.

“Not all segments of detachable magazines could be counted due to lack of public information or availability of records. For example, detachable shotgun magazines are prevalent in certain shooting sports and tactical applications but were not counted,” the group wrote. “No reliable data exists prior to 1990 to estimate historic detachable magazines that may still be available for sale or in working condition. This is due to lack of ATF AFMER reporting prior to 1990.”