Legal weapons used in the San Bernardino attack, courtesy of the San Bernardino County Sheriff ‘s Department

New York City Transit officials are planning to release inert gas and DNA particles into the subway system in order to study the effects of a terrorist bio-attack, the New York Post reports. This is a waste of time, because terrorists are much more likely to just kill us with guns.

According to the Post, “non-toxic” materials will be pumped into “the subway at three stations and [the MTA will] take samples at approximately 55 subway stations in Manhattan and parts of Brooklyn and Queens.” If you look at the Homeland Security document that outlines the exercise, the reasoning seems clear enough:

Subways are attractive targets for terrorists to release a biological weapon due to the low physical security and rapid agent dispersion from train and passenger activity. Subway dispersion models have been created to aid in understanding where biological particles travel after a release. These models help in both pre- and post-attack planning for first responders. Pre-attack planning includes identifying ideal locations for biodetection technologies. Post-attack planning includes determining the source location for attribution, identifying exposed passengers, and aiding the remediation effort (e.g., mapping, decontamination). While the subway dispersion models are critically important for homeland defense, there is little quantitative evidence as to their accuracy due to limited testing.

This would be a worthwhile study if there were any reason to expect such an attack from the Islamic State. But I hope our finest national security minds grasp that no such threat seriously exists. Unless you’ve been dropped into a Tom Clancy novel, PlayStation game, or the Tokyo subway system in 1995, there’s virtually no reason to expect to be gassed or exposed to some sort of pathogen-bomb the next time you ride the subway.

Not to say ISIS wouldn’t love to release sarin on the L train or flood Grand Central Station with smallpox—what self-respecting jihadi wouldn’t!—but those sorts of attacks are incredibly hard to pull off. Biological and chemical weapons require extremely high degrees of technical sophistication and scientific knowledge to execute, before you even get into the difficulties involved in acquiring and transporting the raw materials. You can’t buy the requisite components of a bio-bomb at Home Depot.

Obviously it’s possible that determined attackers with sufficient resources could pull off such a spectacular attack; the 9/11 attacks were themselves extraordinarily complex. But why would a would-be attacker pursue an even more complex—and, frankly, extremely unlikely to succeed—scheme, when one can already legally and easily purchase just about anything one might need for a premeditated act of mass violence?

Pressure cooker bombs (or any explosive loaded with shrapnel, as was used yesterday in Brussels) can be built with cheap parts and PDF instructions. And even bombs are fallible (recall the malfunctions and failures of the Paris attacks) compared to the sheer, stupid simplicity of a gun. Remember: The aforementioned Tokyo sarin attacks—the only real precedent for the sort of attack New York is prepping for—happened in a country where private firearm ownership is effectively nonexistent.

When you consider how much ISIS has leaned on “lone wolves” and very small cells half a world away from Syria, guns make even more sense, and bio-weapons seem all the more stupid and impossible. A bomb (even without an added agent) requires some skill. A bomb has many points of failure. A bomb can be a dud, or detonate prematurely. A bomb leaves a paper trail of components and receipts and residues. A bomb takes time to source and assemble.

Now consider a gun. A single, 100% legal AK-47 purchased at the same store used by the San Bernardino couple carries thirty rounds, plus one in the chamber. A good shot could shoot thirty-one people in a New York Subway station (or train) without reloading. A very good shot would kill most of those people, exceeding the death toll in yesterday’s Brussels attack. A few spare magazines could triple the capacity for bloodshed and horror. And—this is the crucial part—even in the hands of a complete fucking idiot who can’t aim a gun to save his life, a gun is still an incredibly effective terror weapon.

An ISIS gunman in the New York subway who emptied his weapon but hit only a couple people would still halt the entire public transit system in the financial capital of the world, scare people away from using it for months, and force some draconian reaction by state and even national officials. Now imagine this kind of attack, but with two, three, or four people at once. Now ask why you would ever even bother with a bomb! The Second Amendment—at least as it is currently interpreted by our courts and understood by our lawmakers—is a would-be terrorist’s best friend.

This is exactly why ISIS doesn’t bother encouraging high tech attacks of the variety Homeland Security is running experiments against. A short ISIS video released in the wake of its attack in Paris, where guns proved to be far more effective than even crude bombs, urged copycats to strike with an equally lo-fi approach: “If you can’t find a weapon, smash their heads with a rock, or run over them with your car and terrorize them.” If the government really wants to protect us from another Paris, they’ll reconsider releasing inert genetic samples into the air and instead consider making it as difficult as possible to buy devices that allow instant, effortless murder.