Just received the new SAR. There is now a company making duckbill chokes. The company is Great Lakes Arsenal, 60233 Northern Ave. Ray, MI 48096-3914, (810)749-9386 e-mail email@example.com. They only do non-ribbed barrels. Don't know if they work on extended tubes or only standard length. The company will not put them on shotguns with reciprocating barrels either. This version is made of 01 oil hardening drill rod and fires into at least a 4:1 horizontal pattern!
I plan on getting one after hearing back from the company. Just don't know whether to put it on the Ithaca or a Mossberg.