Got a Mossberg 12 ga combo, but wanted a 18" cyl bore barreled 12 ga for home security like the Mossberg Maverick. Well, in these times, forget about it! None to be had on the planet. Sooo, figured I'd buy a smooth bore 18" barrel for the 500. First of all they want $200, second of all none on the planet. Sooo, found a brand new 28" vent rib mod choke on fleabay for $82 free shipping. Took a sawzall to that puppy, a little magic marker to the bare metal + voila.