The federal judge considering a landmark class action settlement involving 7.5 million allegedly defective Remington rifles is raising new concerns about what he called the "exceedingly small" number of gun owners who have filed claims to get their guns fixed.

"It seems inconceivable to me that someone would have a firearm that might injure a loved one and not have it fixed," said U.S. District Judge Ortrie Smith at the start of a three-hour hearing in Kansas City on Tuesday to consider final approval of the settlement.

As of Monday, only about 22,000 owners have filed claims in the two years since the settlement was announced, attorneys say. With as many as 7.5 million guns, that's a claims rate of about 0.29 percent. Critics, including attorneys general from nine states and the District of Columbia, are urging Smith to reject the deal, in part because of those numbers. They also complain that the settlement sends a mixed message by allowing Remington to continue claiming the guns are safe.

The case involves some of Remington's best-selling guns including the wildly popular Model 700 rifle, which CNBC first investigated in 2010. Lawsuits have alleged that for decades, Remington covered up a design flaw that allows the guns to fire without the trigger being pulled, resulting in dozens of deaths and hundreds of serious injuries.

Remington has consistently maintained the guns are free of defects and that the incidents are the result of user errors. But in late 2014, the company said that to avoid drawn-out litigation, it was agreeing to replace the triggers on millions of guns free of charge.