WASHINGTON — Few places have seen the National Rifle Association wield its might more effectively than Florida, where it has advanced a sweeping agenda that has made it easier to carry concealed weapons, given gun owners greater leeway to shoot in self-defense and even briefly barred doctors from asking patients about their firearms.

To many of its opponents, that decades-long string of victories is proof that the N.R.A. has bought its political support. But the numbers tell a more complicated story: The organization’s political action committee over the last decade has not made a single direct contribution to any current member of the Florida House or Senate, according to campaign finance records.

In Florida and other states across the country, as well as on Capitol Hill, the N.R.A. derives its political influence instead from a muscular electioneering machine, fueled by tens of millions of dollars’ worth of campaign ads and voter-guide mailings, that scrutinizes candidates for their views on guns and propels members to the polls.

“It’s really not the contributions,” said Cleta Mitchell, a former N.R.A. board member. “It’s the ability of the N.R.A. to tell its members: Here’s who’s good on the Second Amendment.”