This kit essentially provides a conversion to 590S functionality, but in a more robust design.  It contains our patented Universal Cartridge Adapter and low-drag no-snag Magazine Follower which allows smooth cycling of 1-3/4" Minishells up to 3" Magnum cartridges in the same magazine.  The adapter is constructed from vulcanized thermoplastic rubber, and the follower is machined from solid 6061-T6 billet aluminum.  This kit is compatible with any Mossberg 12-Gauge pump-action firearm with a 3" Chamber and machined grooves in the receiver. 

Not compatible with 590R.

Please note there may be a short break-in period for some adapters after installation.  Cycle a few magazines of full-size shells if you initially experience issues with 1-3/4" shells, please reach out to us if problem persists.  

*The Cartridge Adapter and Magazine Follower are optimized to function as a pair, but the factory follower may function as well for those that do not wish to remove it.