A provocative NDP billboard campaign attacking the Conservatives' decision to end the long-gun registry had to be changed at the last minute when it was revealed the ad targets the wrong gun.

Featuring a semi-automatic weapon illustrated in stark colours with the words "No More Safeguards," the adverts were set to go up on billboards in three cities. But the party has been forced to scramble because the gun used in the image is restricted and will still have to be registered, even after the registry is gone.

Initially, the party planned to use an image of a Ruger Mini 14, which is a semi-automatic weapon that was used in the Polytechnique shooting spree in 1989.

However, the ad featured the "Tactical" version of the Ruger Mini 14, which still must be registered even without the long-gun registry.

Marc Lepine, who opened fire in the Polytechnique massacre, used the "Ranch" edition of the Ruger Mini 14, which remains a non-restricted firearm. It won't have to be registered after the long-gun registry is finished.

The differences between the Ranch and Tactical versions of the Ruger Mini 14 are more than just cosmetic. While both are semi-automatic weapons, the Tactical has a shorter barrel and resembles a military machine gun. Shorter barrels are considered more dangerous because they can be concealed easier.

The Ranch, meanwhile, has a longer barrel and looks more like a hunting weapon.

Now, the party plans to use the Steyr HS .50, which is a sniper rifle not restricted by Canada's gun laws, NDP national director Chantal Vallerand told The Globe and Mail.

"We are updating it," she told the paper.

Still, the Ranch has the notorious distinction of also being the weapon used by Anders Breivik during the murder spree that left 77 people dead in Norway in July of this year. Breivik's rifle was a heavily modified version, according to reports.

Additionally, CTV Power Play host Don Martin said that the NDP campaign is confusing, given that there won't be a federal election for four more years.

While the Conservatives have often mounted attack campaigns on the Liberals in recent years, those attacks were made in a minority government environment, where an election was possible at any time.

"It would seem on the surface to be pointless," Martin said of the campaign.

However, he noted that the NDP could be launching the ads to mobilize their base, increase campaign donations and hopefully strike a chord with the public.

Martin added that when the federal subsidies for political parties end in the coming term, the NDP will be forced to rely on donations to fund their operations.