Jessie Heddings lives on the front lines of a border war. If he is forced to surrender, it will be at the hands of a surveyor.

Heddings, a barrel-chested man of 60, has lived in Catlett in Fauquier County most of his life. But under a proposal now being considered, he soon could be a resident of Prince William County.

"I'll probably have to change counties without taking a single step or lifting a hand," said Heddings, "but I don't lke it."

Heddings is one of nearly 30 landowners who lives along a disputed 20.7-mile boundary that separates Fauquier and Prince William counties. The original boundary was established in 1902, and surveyors set conical, black granite markers along the line. Over the years, most of the markers have disappeared, said Amil K. Clark, a Prince William mapping specialist who estimates a new survey to reestablish the 1902 line would cost about $50,000.

The dispute, officials in both counties say, has been shimmering for more than a decade. It erupted into a full-blown battle last year, says Prince William County assessor Ben Kelsey, when Prince William decided to follow a state attorney general's ruling of 30 years ago requiring neighboring counties to assess land tracts up to the county line.

Before that, Kelsey said, he and Jane Childs, the Fauquier commissioner of revenue, had negotiated every year, dividing the disputed properties between the two counties. The major consideration was to make such each county got an equal share of the tax revenues.

"In effect, we haven't been following the (1951) attorney general's ruling," conceded Kelsey.

The Prince William decision has had one very tangible result for landowners such as Heddings. This year, for the first time since he took over the homestead from his father 31 years ago, Heddings -- and the other landowners -- received tax bills from both counties.

"I'll pay one, but I can't pay both," said Heddings, who lost most of his crops to this year's drought and faces a 1980 tax bill that is 2 1/2 times higher than last year.

Heddings owns 200 acres along Dorrells Run in the lap of the Blue Ridge Mountains, where he grows barely, hay and corn and operates a dairy. His son, John, 24, helps with the farm work and is visibly angered over the twin bills.

"They want us to pay taxes in both counties," he said, "but we can only have a say in one." That, says John, is taxation without representation.

At the Heddings farm, the proposed boundary line would move nearly 300 feet toward Prince William. That would place much of Heddings' Fauquier acreage, including his house and farm buildings, in the geographic fold of Prince William.

The tax rate in Prince William is $1.41 for each $100 of assessed value; in Fauquier the rate is 58 cents for each $100.

"They're going to kill the goose that lays the golden egg, and they don't even care," said Heddings, who claims he talked to Prince William officials in an effort to settle the billing dispute. "They just said that's your problem. They were downright arrogant."

Other parcels, such as Buckland Farm, probably would have lower tax bills under the boundary change being considered. According to Prince William officials, the farm now is in Prince William, but under the boundary change more than 170 acres would be included in the lower tax brackets of Fauquier. The farm's owner, Thomas M. Evans, could not be reached for comment.

One landowner, James L. Cooke, already has taken a line of resistance over the double billing. Cooke, a retired Arlington contractor, lives in Greenwich, a small Fauquier community within eyesight of the Prince William line. Like the other landowners, he received tax bills from both counties.

"Fauquier County told me to pay who I have alway paid so that's what I'm going to do," said Cooke, who received six bills totaling $2,039.76 on five tracts of land -- five from Prince William and one from Fauquier. "I'm not paying Prince William until the judge comes and tells me to." The due date on the bill is Dec. 5.

The dispute now angering landowners on both sides of the line started with a rock festival nearly 11 years ago, according to Prince William officials. Some nearby residents complained about the concert to Prince William officials, and therein came the rub.

The concert was at Thorofare Gap in Fauquier; the only access was on a Prince William County road.

"We don't know who had jurisdiction," said T.A. Emerson, county attorney in Prince William.

Added Prince William assessor Kelsey, "That caused everyone to start looking at the maps and the law."

Prince William's board of Supervisors recently voted to pay half the $50,000 cost for a new survey, but so far, Fauquier has not.

Steve Crosby, the Fauquier County administrator, said the two counties are close to reaching an agreement. "But we don't just want to give these people and the land up without a fight," said Crosby, who describes the situation as "a real mess."

And, he admits, Fauquier is not anxious to lose the 400 acres that the proposed new border would place in Prince William.

Still, says Crosby, he expects the Fauquier supervisors to eventually agree to the survey.

Despite the move toward an agreement, there are Prince William supervisors who question the value of a new survey.

"After Fauquier was carved out of Prince William in 1759 they set a boundary in 1902 and now it's 1980. It's been good for 88 years and it sure as hell should be for the next few years," said Prince William Supervisor Joseph D. Reading, whose Brentsville district contains disputed land. "But maybe it will be worth it to get this thing straightened out."

Even a new survey will not be complete, admits Prince William official Clark. The northern section of the line probably will not be surveyed, he said, because it follows the ridge of the nearly inaccessible Bull Run Mountains. The southern section includes a part of Quantico Marine Base that is laced with live ammunition.

"We won't bother with that. You couldn't go in there safely even with a minesweeper," said Clark. "Nobody needs to get killed over this."