Mesa Tactical announced their 24 inch rail system for Remington and Mossberg shotguns.
The Picatinny rail system is intended to be used with high-tube telescoping stock conversion, but seems like it can be used as a stand-alone product.
Price(MSRP) for the rail seems to be from $145 to $215, while the whole stock kit will be $450 to $600.
From: Mesa Tactical.