“Meet the Press” moderator David Gregory sparked a police investigation over his use of a prop – what he said was a 30-round magazine – during his grilling of National Rifle Association President Wayne LaPierre on Sunday.

The investigation comes after NBC reportedly sought advice from the Washington, D.C., Police Department about the use of the gun clip.

During Sunday’s broadcast, Gregory displayed what appeared to be a gun magazine that could hold 30 bullets when he asked LaPierre if banning such magazines would help to curb gun violence like the Sandy Hook Elementary School shooting.

“Here is a magazine that carries ammunition for 30 bullets,” Gregory said, while holding up the prop during his interview with LaPierre. You can see Gregory displaying the gun clip here.

“Now isn’t it possible that if we got rid of these, if we replaced them and said,  ‘You could only have a magazine that carries five bullets or 10 bullets,’ isn’t it just possible that we could reduce the carnage in a situation like Newtown?” the “Meet the Press” moderator asked the NRA president.

“I don’t believe that’s going to make one difference,” LaPierre responded.

“There are so many different ways to evade that. Even if you had that for 10 years, when [U.S. Sen.] Dianne Feinstein passed that [assault weapons] ban in ’94, it was on the books. Columbine occurred right in the middle of it. It didn’t make any difference,” he added, referring to the mass shooting at the high school in Colorado.

Police are investigating Gregory’s use of the prop because of a potential violation against the Washington, D.C., code, Politico reported. “Meet the Press” is broadcast from NBC’s Washington offices.

The code states that, “No person in the District shall possess, sell, or transfer any large capacity ammunition feeding device regardless of whether the device is attached to a firearm. For the purposes of this subsection, the term ‘large capacity ammunition feeding device’ means a magazine,” among other devices, according to Politico.

D.C. police confirmed to the political website that it was “investigating the matter,” which it called “the ‘Meet the Press,’ David Gregory incident.”

The investigation, which was reported on Tuesday by Politico, comes after D.C. authorities urged NBC not to show the magazine on television. The network reportedly asked the police department for advice on the legalities of the magazine prop.

“NBC contacted [the D.C. Metropolitan Police Department] inquiring if they could utilize a high capacity magazine for their segment,” Gwendolyn Crump, a police spokeswoman, said in an email to Politico. “NBC was informed that possession of a high capacity magazine is not permissible and their request was denied. This matter is currently being investigated.”