The Bushmaster is very popular with former military personnel, said Don Davis, who owns Don's Guns in Indianapolis. The store has one of the largest firearms selections in the country.
According to officials, one of the suspects, John Allen Muhammad, served in the Army as a machinist, and was discharged in the mid-1990s.
"We get a lot of guys who come in and say 'That's the gun I had in the military,'" said Davis. "This guy they got in Maryland was in the military. It looks exactly like the gun he had in the military."
Don's Guns sells about two Bushmasters every week, Davis said.
The Bushmaster is a close replica of the M-16, which is the gun actually used by the U.S. military. The two models resemble each other closely. Both generally cost $700 to $900. In the West, many people use the guns for "varmint hunting," Davis said: shooting from long distances at prairie dogs, coyotes and other small animals.
According to a senior Defense Department official, Muhammad had no training as a sniper while in the military. But even if he had no training, he could still have used the gun effectively from long range, Davis said.
"It would absolutely make a good gun," he said. "Anybody that had that gun sitting on a tripod, with a scope, be it you, your wife, anyone, could take that gun and hit something 500 yards away. So these shots (in the DC area), which are 150 yards away, anybody could do that."
The gun recovered from the trunk was a Bushmaster semi-automatic rifle, .223 caliber, model A-35, XM15.
Sources say the gun had a flash suppressor on it. This device hides the muzzle flash when the gun is fired, making it difficult to detect where the shot originated.
According to the Bushmaster Web site, in 2000, the company sold 39,932 automatic rifles, almost 10,000 more than its closest competitor, Colt. "BUSHMASTER IS #1 AGAIN," the release reads. "The combination of Bushmaster's top quality materials, mil. spec. manufacturing, great accuracy and durability have again proved to be the best selling AR type rifle in the U.S.A."