The Co-witness Ready Optic Mount (CROM) is a direct mount for
attaching a Trijicon RMR to your Mossberg shotgun. Using the existing
drilled and tapped hole pattern found on many factory Mossberg 500s,
590s, and 930s, the mount eliminates the need for a picatinny rail by
directly mounting the optic to the receiver. This allows the optic to
sit much lower, providing a consistent and proper cheek weld.
The CROM utilizes an XS rear ghost ring that is adjustable for both
windage and elevation. This gives you the ability to co-witness the rear
ghost ring and an appropriately sized front sight with the red dot,
allowing an emergency backup sighting system in case of optic failure.
Front sights from XS, Wilson Combat, Vang Comp, etc that are designed to
work with ghost rings will be compatible with the CROM’s rear aperture.
Front sights with a height over bore (top of the inside of the barrel
to the top of the front sight) of approximately 0.75" should be able to
achieve a usable co-witness. The height of the CROM aperture is designed
around the factory front ghost ring sight of the Mossberg 590A1
If your Mossberg shotgun is not drilled and tapped using the Mossberg pattern, consult a qualified gunsmith.