- A flat washer MUST be used with the factory stock bolt. A washer is included with the stock. The Hogue stock is designed to reuse the factory stock bolt with the addition of the flat washer. - The stock bolt (not included) is a 5 ½”long 5/16” – 18 TPI with a flat washer, available at any quality hardware store, gun parts retailer, or from Mossberg directly. You must use this bolt when changing from a pistol grip or Tamer to a butt stock. Tamers/Pistol grips use a short bolt that is included with the Tamer (no washer needed). Also fits: - Model 590A1 - Maverick model 88 - Other Mossberg pump shotguns that are copies or variations of the 500. - 510 Mini Does not fit: - 930 series or any other auto shotgun. - Break open guns - Flex system shotguns Please note: Some .410 models will not fit. Please call Hogue Customer Service to determine if the stock will fit your rifle. You may be required to provide measurements.