When liberals from Northern Virginia start talking about legislation to limit handguns, opponents of such measures know at least one Northern Virginian will be on their side.

That is 38-year-old Lawrence D. Pratt of Fairfax County, a baby-faced professional gun lobbyist starting his second year as a delegate in the Virginia House.

In Richmond, Pratt rarely finds the need to mention his opposition to gun control, an issue that has never gone anywhere in the General Assembly and is expected to fall flat again this year.

"I don't really have to talk about those things down here," says Pratt. "It's one of those bedrock issues in Virginia that's never going to change. Virginia is not a problem area for people who support the Second Amendment."

Pratt is widely regarded as one of the most conservative members of the General Assembly. He opposed most government spending, he was one of the organizers who last year engineered a takeover of the Virginia Conference on Families by anti-abortion, anti-feminist conservatives and he has been closely allied with the supporters of Lynchburg evangelist Jerry Falwell.

The soft-spoken Pratt was elected to the General Assembly in 1979 after outspending all other contenders in his five-member district almost 2-to-1. Major factors in his fundraising efforts were his work as a full-time lobbyist for the Gun Owners of America, a group that spend $842,000 last year in support of candidates, and his connections with Joseph Coors' Heritage Foundation and other groups now being counted among the "New Right."

The presence of Pratt in the Northern Virginia delegation, observers say, is just one sign of the increasing conservatism of those suburbs. Northern Virginia, where community leaders once pointed to their resistance to segregation as their proudest accomplishment, for many years painted itself as a bastion of Virginia liberalism. But, social scientists now say, a massive influx of well-to-do conservative voters over the past few years is rapidly changing all that.

While a conservative like Pratt might be popular among the Byrd-machine remnants of Virginia's old guard, most other legislators in Richmond -- including other Republicans -- criticize him as a right-wing ideologue elected by single-issue groups. They say his inflexibility on narrow issues makes him almost impossible to work with. Rather than help write the legislation to solve problems, many say, Pratt takes a negative approach.

"Larry Pratt is one of the most consistent people I know," says state Sen. Wiley B. Mitchell, a Republican from Alexandria. "He's against everything."

Not surprisingly, such a reputation does little to help Pratt win approval for his pet legislation. Of eight bills he introduced last year, only one -- a minor housekeeping measure -- survived. Amond his proposals was a bill to ban obscene or nude drawings on motor vehicles. The bill died after several legislators pointed out that the state would have to severely modify its official Virginia seal, which includes a picture of a nude woman.

Another bill, which would have outlawed the sale and possession of drug paraphernalia, seems more likely to win approval this year, largely because court decisions in the past year have indicated such a law could withstand a constitutional test.

A survey of legislators, journalists and state officials, conducted by the Norfolk Virginian-Pilot this year, ranked Pratt as the least effective member of the House of Delegates.

The criticism by his colleagues and others doesn't seem to bother Pratt, who sometimes refers to himself as a lightning rod of conservative opinion.

"(Liberals) come up with so many bad ideas," Pratt said, "that we have to get rid of (those ideas). They're the ones who are negative."

Still, say his colleagues, Pratt's personality sometimes thwarts his efforts to influence legislation.

"There's a tendency for Larry to believe what's right is right and what's wrong is wrong," says Warren Barry, a Republican colleague from Fairfax. "Inflexibility is not good when you're in the legislative process. It's a system of give and take." g