On one level, what is happening here and elsewhere simply reflects supply and demand. The gun industry has spent decades stoking demand for the AR-15 and rifles like it. Now, after the mass killings in Aurora, Colo., and Newtown, President Obama wants to reduce the supply. He has asked Congress for tougher controls, including a ban on what are commonly called “military-style assault weapons”; the Senate Judiciary Committee held a hearing on gun violence last Wednesday. Many enthusiasts are rushing to buy one of the rifles now, in case the president prevails.

But how did gun makers stir up the demand for these particular guns in the first place? The answer is a story of shrewd advertising, aggressive marketing and savvy manufacturing — a virtual recasting of the place of guns in American life. With speed and skill, firearms manufacturers transformed a niche market for the AR-15 and similar rifles into a fast-growing profit center.

When certain rifles and features were banned under federal law from 1994 to 2004, gun makers tweaked their manufacturing specifications — and introduced more AR-15-style rifles than ever. With ads celebrating the rifle’s military connections, they lured a new and eager audience to weapons that, not long ago, few serious gun enthusiasts would buy.

It might seem remarkable, given the national conversation about gun control, but guns are a relatively small business in the United States. Sales of commercial guns and ammunition — as opposed to those sold to the military and police — amounted to about $5 billion in 2012. That’s less than half of the profits that Apple earned in the final 13 weeks of last year. But despite the headlines, and partly because of them, commercial gun sales are growing. Last year, they were up 16 percent industrywide, according to estimates from the National Shooting Sports Foundation, an industry trade association. Semiautomatic rifles like the AR-15 are responsible for a significant share of that growth.

By now, many Americans probably recognize the AR-15, whether or not they recognize the term. Unlike its military counterpart, the M-16, the civilian AR-15 cannot spray a continuous stream of ammunition with one pull of the trigger. But, as a semiautomatic, it can fire individual bullets as fast as the trigger can be squeezed. By design, it looks and feels like something commandos might carry. That is part of its appeal, and of manufacturers’ pitch.