In a normal legislative battle, there comes a point when advocates have to stop letting the perfect be the enemy of the good. When it comes to gun control, the calculus is different: You have to stop letting the adequate be the enemy of the incremental but significant.

That maddening fact is why the recent uproar over assault weapons is so dangerously misplaced. I’m all for limiting access to assault weapons, although the impact would be more symbolic than practical.

But reinstating the ban was never in the cards. The best that could be realistically hoped for was a Senate floor vote on an assault-weapons amendment — a vote doomed to fail.

So pounding Senate Majority Leader Harry Reid (D-Nev.) for announcing that assault weapons would not be part of the proposal he brings to the Senate floor has the situation completely backward.

If Reid had included assault weapons, it would have doomed the larger effort — in particular, the chance of expanding background checks for gun buyers. Requiring background checks for nearly all gun purchases is a change that is simultaneously more effective than banning assault weapons and more politically achievable.

Which is why the real worry of gun control advocates shouldn’t be Reid’s supposed perfidy in jettisoning assault weapons — it’s whether the background-check measure passed by the Senate Judiciary Committee is too strong even to make it to the Senate floor.

It pains me to write those words, but this is the legislative reality. The behind-the-scenes Senate negotiating over background checks is being conducted by Democrats Charles Schumer (N.Y.) and Joe Manchin (W.Va.) and Republicans Tom Coburn (Okla.) and Mark Kirk (Ill.).

They largely agree that the requirement for background checks should be expanded to cover most private sales — at gun shows, over the Internet and in other, non-family transactions. This would close a gaping loophole — ­some estimates put the number as high as 40 percent of gun transfers — in the existing system.

The National Rifle Association argues that such checks won’t deter felons and other ineligible purchasers who are determined to acquire guns. But the numbers belie that contention: More than 2 million would-be purchasers have been denied since the existing system was launched in 1994.

No doubt people managed to buy guns anyway. But others were likely deterred — and a system of universal checks would make illegal purchases even more difficult.

The real holdup in the negotiation over expanded background checks involves recordkeeping — specifically, whether private sellers should be subjected to the same requirement as licensed firearms dealers to maintain sales records.

Of course they should. In a perfect world — that is, in a world without the NRA — guns would be treated like automobiles. The government knows who owns a particular car and when, and to whom, it is transferred. These records are computerized and searchable.

Ann Telnaes animation: Biggest bank account wins? (Ann Telnaes/The Washington Post)

The current recordkeeping system for guns is straight out of Dickens. Manufacturers know where they have sent a new gun. Afterward, the paper trail becomes just that — on paper, in boxes stored in dealers’ basements — and often runs cold after the first seller or two. The evidence of the check itself must be destroyed within 24 hours.

So how important is it to require private sellers to keep these records? More precisely, is the recordkeeping requirement so essential that it is worth demanding at the risk of losing expanded checks entirely?

Some gun-control purists argue that omitting such a requirement would make the expanded checks toothless, leading sellers to ignore them altogether. Some probably would.

Yet restaurants card would-be drinkers, grocery stores ask for proof of age from prospective tobacco purchasers — all without keeping records of such checks. The incentive to obey comes from the fact of the law’s existence and the risk of random sting operations.

A second argument for recordkeeping is that it helps police trace guns used in crimes. Again, true. But the current recordkeeping is far from perfect, and, in any event, the point of background checks isn’t to solve gun crimes — it’s to prevent them.

The criticisms of recordkeeping — that it’s unduly burdensome, a step down the slippery slope to gun registry — are specious and paranoid. That’s infuriating but irrelevant. Background checks with recordkeeping won’t get the 60 votes necessary to pass the Senate or stand any chance in the House. Background checks without recordkeeping will.

I’m reliably told that, despite its continuing fulminating, the NRA may not actively oppose expanded checks without recordkeeping. Such a measure would be a huge, if imperfect, achievement — a possibility to be seized, not squandered.

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