Remington Outdoor, one of the oldest firearm manufacturers in the United States, filed for bankruptcy protection on Sunday amid mounting debt and declining sales.

The gun maker had said last month it was nearing a bankruptcy filing, which it made on Sunday in federal bankruptcy court in Delaware. In its Chapter 11 filing, Remington said it had between $100 million and $500 million in debt and would continue to operate while under bankruptcy protection. It estimated that its assets were between $100 million and $500 million.

Remington did not immediately respond to a request for comment on Sunday evening.

The company, which was founded in upstate New York in 1816 but is now based in North Carolina, was acquired in 2007 by the private equity firm Cerberus Capital Management for $118 million. The firm rolled it up with other gun manufacturers, including the maker of the Bushmaster rifle, into a conglomerate called Freedom Group.