Key measures of New York's tough new gun law are set to kick in, with owners of guns now reclassified as assault weapons required to register the firearms and new limits on the number of bullets allowed in magazines.

As the new provisions take effect Monday, New York's affiliate of the National Rifle Association said it plans to head to court to seek an immediate halt to the magazine limit.

Gov. Andrew Cuomo calls those and other provisions in the state's new gun law common sense while dismissing criticisms he says come from "extreme fringe conservatives" who claim the government has no right to regulate guns.

"Yes, they are against it, but they are the extremists and the extremists shouldn't win, especially on this issue when it is so important to the majority," Cuomo said in a radio interview Wednesday. "In politics, we have to be willing to take on the extremists, otherwise you will see paralysis."

New York's new gun restrictions, the first in the nation passed following December's massacre at a Connecticut elementary school, limit state gun owners to no more than seven bullets in magazines, except at competitions or firing ranges.

The new regulations in New York commence as the U.S. Senate prepares to debate expanded gun legislation and weeks after Connecticut joined Colorado in signing into law tougher new gun restrictions.

The New York State Rifle & Pistol Association, the state's NRA affiliate, has a pending federal lawsuit against the new provisions. It plans to ask a judge Monday for an immediate halt to the magazine limit. The new registrations, required over the next year, will be the group's focus later.

The law violates the constitutional rights of law-abiding citizens "to keep commonly possessed firearms" at home for self-defense and for other lawful purposes, the New York State Rifle & Pistol Association said in court papers. It is advising members to obey the law in the meantime.

"We are lawful and legal citizens of New York state and we always obey the law," association President Tom King said. "It's as simple as that."

State Police planned to post forms on their website for registration starting Monday. Owners of those guns, now banned from in-state sales, are required within a year to register them. Alternatively, they can legally sell them to a licensed dealer or out of state by next Jan. 15.

Rich Davenport, recording secretary of the Erie County Federation of Sportsmen's Clubs, said their nearly 11,000 members are united in opposition to the law, which he considers a hasty, illogical and emotional response to the Newtown, Conn., school shooting. He also questioned likely compliance with the registration requirement.

"I'm guessing it'll be pretty low," said Davenport, a longtime hunter. He said that even though he's not personally affected by the registration provision, "I'm offended as an American."

The toughest part of the new statute -- banning in-state sales of those guns newly classified as "assault weapons" -- immediately took effect Jan. 15. The new classification related to a single military-style feature, such as a pistol grip on semi-automatic rifles with detachable magazines. Other listed features include a folding or thumbhole stock, bayonet mount, flash suppressor, or second protruding grip held by the non-trigger hand.

It requires owners to register an estimated 1 million guns previously not classified as assault weapons by April 15, 2014, though law enforcement officials acknowledge they don't know exactly how many such guns New Yorkers have.

The assault weapon definition also applies to some shotguns and handguns. They include shotguns that are semi-automatic, or self-loading, and have another feature, such as a folding stock, a second handgrip held by the non-shooting hand or the ability to accept a detachable magazine.

Also covered are semi-automatic pistols that can take detachable magazines and have another feature, such as a folding or thumbhole stock, a second handgrip and a threaded barrel that can accept a silencer.

Many county boards in New York have passed resolutions urging at least partial repeal of the law while warning that new registration requirements would be a costly burden on them.

Herkimer County Clerk Sylvia Rowan said Thursday she had received no registration forms for those guns. "There's a lot of confusion on this," she said.

Rowan noted that she had received few formal requests filed from the holders of the county's 12,000 pistol permits to exempt their information from public disclosure, something else authorized under the new law.

Passed Jan. 15, a month after the school shooting in Newtown, Conn., the statute originally banned magazines with more than seven bullets effective April 15. Connecticut officials said that shooter Adam Lanza used a semi-automatic Bushmaster AR-15 and five 30-round magazines to kill 20 children and six adults in minutes.

However, acknowledging that manufacturers don't make seven-bullet magazines, the Cuomo administration and New York lawmakers amended their law on March 29, keeping 10-bullet magazines legal but generally illegal to load them with more than seven bullets.

The new Colorado bill, signed into law last month, bans ammunition magazines that hold more than 15 rounds.