A top police representative on Tuesday said that there is no history of criminals using a round popular among AR-15 rifle shooters against officers, undermining the Obama administration's argument for banning the 5.56 M855 "lightgreen tip."

"Any ammunition is of concern to police in the wrong hands, but this specific round has historically not posed a law enforcement problem," said James Pasco, executive director of the Washington office of the Fraternal Order of Police, the world's largest organization of sworn law enforcement officers, with more than 325,000 members.

He told Secrets that the round used mostly for target practice "is not typically used against law enforcement."

While he said that he is "not finding fault" with the surprise move last month by the Bureau of Alcohol, Tobacco, Firearms and Explosives to classify the round as "armor piercing" and then ban it, Pasco added, "While this round will penetrate soft body armor, it has not historically posed a threat to law enforcement."

That view not only counters BATFE's reason for proposing the ban, it also challenges the White House endorsement of the ban. Spokesman Josh Earnest said Monday, "we are looking at additional ways to protect our brave men and women in law enforcement and believe that this process is valuable for that reason alone. This seems to be an area where everyone should agree that if there are armor-piercing bullets available that can fit into easily concealed weapons, that it puts our law enforcement at considerably more risk."

The administration's effort is under fire on Capitol Hill where 55 percent of all House members have signed a letter challenging BATFE's proposal.

Led by House Judiciary Committee Chairman Rep. Bob Goodlatte and the National Rifle Association, 235 members have signed the letter. The signatures came in at a record pace since Goodlatte's team and the NRA have been circulating it for just three business days.

A similar effort is moving quickly through the Senate, led by Senate Judiciary Committee Chairman Sen. Chuck Grassley.

As with most rounds used in rifles, the 5.56 M855 will shoot through soft body armor, but was granted an exemption to longstanding police protection legislation because it isn't used by criminals who typically use smaller pistols.

BATFE said that with the popularity of AR-style pistols growing, the weapon poses a new threat to police. But foes of the bullet ban say that criminals are unlikely to spend the $1,000 or more to by one and also that at about 20 inches long, it isn't considered a concealed weapon.

Many gun enthusiasts believe that the proposed bullet ban, up for public comment, is a backdoor bid to cut the popularity of the AR-15, the nation's most popular gun, one critics call an "assault weapon" and a target of liberals and President Obama.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.