Federal Cartridge Co. in Anoka is laying off 40 to 50 production workers after catching up on significant back orders for its pistol and small rifle ammunition, officials confirmed Wednesday.

Federal Cartridge, which is a division of Eden Prairie-based defense firm Alliant Techsystems Inc. (ATK), will employ about 1,000 workers after the layoffs. Affected employees were notified this week, said ATK spokesman Bryce Hallowell.

The layoffs come about a year after Federal Cartridge added nearly 150 workers to help catch up on back orders. The Federal Cartridge plant in Anoka manufactures ammunition mostly for law enforcement, hunters and civil training exercises.

ATK, which generated $4.2 billion in fiscal 2008 sales, recently reported second-quarter armament sales of $422 million, a 19 percent jump from a year ago.

The company is the largest small-caliber ammunition maker in the world. It makes military-grade ammunition in Missouri and in other plants around the country.