New Haven 600 is a series of pump-action shotguns manufactured by O.F. Mossberg & Sons on behalf of department stores, most notably the Montgomery Ward Company, Western Auto, and other retail stores. New Haven is one of O.F. Mossberg & Sons' private, promotional brands. The New Haven 600 is identical to the Mossberg 500 from O.F. Mossberg & Sons, with the addition of an anti-rattle system in the magazine tube, and the top of the receiver is not drilled out of a scope mount. Many of the 600AT models came with adjustable C-Lect Chokes. The 600 series comprises widely varying models of hammerless, pump action repeaters, all of which share the same basic receiver and action, but differ in bore size, barrel length, choke options, magazine capacity, and "furniture" (stock and forearm) materials.

New Haven 600
New Haven 600AT
Type	Shotgun
Place of origin	United States
Service history
In service	1977–present
Production history
Designed	1960
Manufacturer	O.F. Mossberg & Sons
Produced	1977–1998
Specifications
Mass	3.3 kg empty - varies loaded
Length	varies with model
Barrel length	14 to 30 inches (350 to 762 mm)
Caliber	12 gauge, 16 gauge, 20 gauge, .410 bore
Action	pump-action
Effective firing range	40 m
Feed system	5 to 8 rounds; internal tube magazine