Mossberg has two solutions.
One is a stock with two interchangeable cheek pads....


DUAL-COMB® STOCK
a Mossberg® exclusive

Developed with the ever-increasing number of scoped shotgun shooters in mind, the Mossberg "Dual-Comb" stock system will help you better set your sights on deer, turkey, clay birds and all your future trophies.
There's no doubt that consistent accuracy requires a consistent aiming position, but as the diagram illustrates, sighting heights for vent rib field barrels and scoped barrels are substantially different.

High and low Dual-Comb inserts provide the correct sighting height and they furnish a consistently solid "cheek-weld" to the stock.

Notice the consistent comb-to-eye distance of references "A & B" - even when the distance of "C" is substantially increased when a scope is used.
When firing a scoped shotgun without a high comb, only a small portion of the chin touches the stock. The result is inconsistent positioning (head wagging) and an understandable tendency to "jerk-the-trigger." The bottom line's the same - accuracy suffers.
Dual-Comb stock inserts are not just an "add-on."
The Dual-Comb stock design employs a thick aluminum base that is permanently fastened into a specially machined wood stock. Each Dual-Comb insert is securely mounted to the aluminum base by two molded positioning pins and a large bolt providing a sturdy, reliable sighting platform from season to season.
Dual-Comb® stocks are available on selected Mossberg® pump action shotguns or as an accessory:
#95059 Honey Satin finish for 12 gauge, 500®, 835® and Maverick® 88™ models.
#14676 Woodland Camo finish for 12 gauge above.
#14764 Honey Satin finish for 20 gauge, 500® models.