The Mossberg "Flex" Shotgun

Based on the Mossberg Model 500 pump shotgun, the Flex system allows you to utilize interchangeable parts to adapt your shotgun for purposes ranging from tactical to hunting. Four base systems are available, the M500 All Purpose, M590 Tactical, M500 Tactical and M500 Hunting. Interchangeable parts are primarily the recoil pad, stock and barrel, no tools required.

Here are the various iterations of the Flex system:

Flex 590 Tactical
Gauge: 12   .   3" Shells   .   Capacity 9   .   Barrel 20"   .   7lb

Flex 500 Tactical
Gauge: 12   .   3" Shells   .   Capacity 6   .   Barrel 18.5" or 20"   .   5.75lb

Flex 500 All-Purpose

Gauge: 12   .   3" Shells   .   Capacity 6   .   Barrel 26" and 28"   .   Vent Rib, Ported   .   7.5lb

Flex 500 Hunting
Gauge: 12   .   3" Shells   .   Capacity 6   .   Barrel 24" and 28"   .   Vent Rib or Vent Rib and Ported   .   7.25lb

It appears that you start by purchasing one configuration and then are free to add the necessary parts in separate kits for each type of shotgun setup. You're looking at $500 to $550 to start with one of the four base models and then it looks like it's around $50 for each component added from there.

The reputable gun magazine article I studied repeated the word "simple" to describe the interchangeability of everything from barrels, to fore-ends to stocks to recoil pads. There are currently six different stocks available,

fixed or adjustable cheek piece, with or without a pistol grip. Finish options include Realtree Max 4, Mossy Oak Infinity, Coyote Tan or OD Green. You also have your choice of recoil pads in various thicknesses. The tactical fore-end has Picatinny rails and grooves for pressure pads for mounting various hardware.

Is this a good shotgun? "Mossberg is the only U.S. manufacturer that meets or exceeds the Mil-S-3433 shotgun specifications for our military." A pretty good endorsement in my book.