here is the RIA link to the gun there is no muzzle brake it has a Slug chole (cylinder) I will also tell you that it has a heavy recoil (IE it kicks) armscor.com/firearms/ria-imports/shotgun-series/single-shot-series/traditional-single-shot-20ga/

Edward, Just cylinder choke. RIA is calling it slug choke. No muzzle break on this shotgun. Hope you purchased one already because they are out of stock.

So the people answering the questions are going off of info they're finding on other sellers website descriptions, and they're is some confusing and conflicting info on various sites.
Id suggest you direct your inquiry to Rock Island Armory by email at support@armscor.com or by phone at 775-537-1444 for any questions, and they will be happy to help you.
Reference UPC
812285025407, or model number TK105

Edward, this UPC code comes with a 20" Contoured Barrel with Slug Choke. --((Specifications and Features)): - RIA Imports Item Number: TK105 - Single Shot Break Action Shotgun - 20 Gauge - 1 Round - 20" Contoured Barrel with Slug Choke - 3" Chamber (also accepts 2-3/4" Shells) - Bead Front Sight - Polymer Stock with a Wood Grain Finish - Silver Receiver and Blued Barrel Finishes - Overall Length 36.61" - Weight 5.1 lbs.