Pretty sure Remington offers a SB brace equipped model from the factory. I built mine before they were offered commercially, went with a Mesa adapter and an original Sig brace, not as much fun as I'd hoped but compact and puts out a lot of 00 pellets .
Just an FYI, they're "firearms" and not shotguns in regard to the law and legal definitions.
www.remington.com/other-products/model- ... -arm-brace