The Standard Manufacturing Door Buster Tactical Breeching Choke is designed specifically for the DP-12 shotgun. It enhances accuracy and a positive grip on the door surface when used as a standoff tool for breeching rounds. It can safely be used with buckshot and rifled slugs as well, so there is no need to remove it from the shotgun when not being used for breeching. This is directly from the manufacturer of the DP-12. Don't settle for third party substitutes.
Specifications and Features:
Standard Manufacturing DP1999
Use with breeching rounds, rifled slugs, buckshot