Or perhaps the 1800s-style weapon, made famous in Hollywood westerns, was a convenient option he pulled off somebody's wall.
Michael Zehaf Bibeau killed Cpl. Nathan Cirillo with a .30-30 Winchester lever-action rifle in Wednesday's attack, an assault that locked down much of Canada's capital and forced the prime minister to take refuge in a closet-like room.
Zehaf Bibeau's rampage ended when authorities shot him dead inside Parliament Hill's Centre Block amid a heavy exchange of gunfire.
The Mounties have since pegged the origin of Zehaf Bibeau's deer-hunting rifle as a central focus of their sweeping investigation.
But Zehaf Bibeau's weapon may also offer clues about the mystery around the true motives of the 32-year-old gunman.
"If he knew anything about this weapon, he knew it would be a one-way trip," said Curtis Rutt, a former Canadian paratrooper and Ontario police sergeant who trained young officers.
"That's not a weapon that you would take to a gunfight and hope that you would ever return."
Rutt said the firearm would be a terrible option in such a situation, since it only holds seven rounds, must be reloaded one bullet at a time and requires the lever to be pulled down before each shot.
That motion, he added, must pull the lever all the way forward and then back — otherwise, the gun won't fire.
Rutt, who said he used to own a similar rifle, figures it would be easy for a shooter under pressure to make errors with the lever, such as failing to pull it forward far enough.
Even though the brush rifle is lightweight and easy to conceal, Rutt recalled how surprised he was to see Zehaf Bibeau wielding one in a photo that circulated soon after the attack.
"It's not a weapon you would use in a stressful situation," he said of the .30-calibre firearm. "It's something that's just fun to shoot for target practice, but it's not something that anyone would ever use for the purpose that he did.
"But, saying that, it might have been the only one he could get his hands on. Maybe he took it off somebody's wall?"
The Mounties have likely explored similar questions since the shooting as they try to determine where Zehaf Bibeau acquired the rifle.
RCMP Commissioner Bob Paulson has said that Zehaf Bibeau, who had a criminal record, would have been barred from buying a firearm.
"In terms of how he got the gun, that is a primary focus of our investigation," Paulson said the day after the attack.
"Certainly, the source of that gun is of tremendous interest to us... we will determine where that gun came from."
In terms of the types of weapon commonly seen in mass shootings in Canada and elsewhere, the archaic, inefficient nature of the Winchester sticks out like a sore thumb.
In 2006, gunman Kimveer Gill wielded a Beretta Cx4 Storm semi-automatic carbine when he attacked Montreal's Dawson College, killing one and injuring 19 others before taking his own life.
Justin Bourque — the perpetrator of a rampage in Moncton, N.B., in June that killed three RCMP officers and injured two others — was photographed carrying what appeared to be an M14 semi-automatic rifle and a six-shot pump-action shotgun.
The motives behind Zehaf Bibeau's attack, meanwhile, remain unclear.
In an article published Friday in Montreal's La Presse newspaper, Zehaf Bibeau's aunt revealed he stayed at her place in Mont-Tremblant, Que., about a two-hour drive from Ottawa, the night before Cirillo was killed.
Reached Friday by The Canadian Press, Monique Bibeau declined to answer questions, but she confirmed the accuracy of the information published in the newspaper report.
She told the newspaper Zehaf Bibeau showed up unexpectedly at her doorstep, even though it had been 10 years since they were last in touch.
Bibeau said they ate dinner together and her nephew told her about working in Western Canada. She added that Zehaf Bibeau, who was raised a Catholic, told her he had converted to Islam.
Zehaf Bibeau's aunt recalled he left her place around 7 a.m. in his Toyota Corolla. Less than three hours later, he shot Cirillo in front of the cenotaph in Ottawa and charged into Parliament for a deadly shootout with police.
Other media reports Thursday indicated Zehaf Bibeau — whose father is from Libya — had been trying to renew his expired Libyan passport, but was denied when officials at the embassy in Ottawa noticed inconsistencies in his application.
Brian Dwyre, who owns Gun-Mart Inc. in Brockville, Ont., said the .30-30 Winchester has absolutely no "military, quasi-tactical value," describing it as a weapon designed during the "horseback era" more than a century ago.
"John Wayne made it famous," Dwyre said.
"Every western had a whole bunch of them. To make a western movie without a Winchester would be like making a fishing show without a motor on the boat."
Even though they are relatively inexpensive — typically about $400 brand new — Dwyre said Zehaf Bibeau might have chosen it as a matter of convenience since they're still common across North America.
"It would not be the weapon of choice for any knowledgeable terrorist."
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