The ammunition, found in an area about 30 feet wide, was traced to the same time period as the 1888 battle, Richardson said.
"The front of the cabin faces almost directly at the spot where these bullets were," Richardson said. "We know from the oral histories that they were shooting out the front of the cabin and from the upper windows. So they're exactly in the spot where they should be."
Also found during the initial search was a piece of charred wood with a nail traced to the McCoy cabin's time period, he said.
Later, an archaeological team led by Kim McBride, co-director of the Kentucky Archaeological Survey, confirmed the location of the McCoy cabin. They found tiny pieces of window glass and ceramics traced to the same period, along with more nails and charred wood.
She would like to return to the site for more excavation work, which could take three to five weeks.
There were other clues connecting the property to the McCoys. The deed to the property was traced back to Randolph McCoy, she said.
"It was kind of a coming together of all the pieces of evidence," McBride said.
The discoveries come amid a surge of interest in the feud that spanned much of the last half of the 19th century. The fighting claimed at least a dozen lives by 1888 and catapulted both families into the American vernacular, becoming shorthand to describe bitter rivalries.
The History Channel aired a three-night miniseries about the feud that set basic cable viewing records. The drama starred Kevin Costner and Bill Paxton as the patriarchs — William Anderson "Devil Anse" Hatfield in West Virginia and Randolph "Ole Ran'l" McCoy in Kentucky.
The New Year's attack was one of the bloodiest episodes in the feud.