20 ga. chamber length Archived Message Posted by PORTER on November 2, 2006, 8:52 pm Michael McIntosh in one of his shotgun books refered to the beginning of 20 ga. LC Smith shotguns being manufactured in 1907 with two and a half inch chambers. When did the chamber size change to two and three quarter inch ? Message Thread: 20 ga. chamber length - PORTER November 2, 2006, 8:52 pm Re: 20 ga. chamber length - Mike November 3, 2006, 6:34 am Re: 20 ga. chamber length - David W November 3, 2006, 6:43 am Re: 20 ga. chamber length - revdocdrew November 2, 2006, 9:05 pm Re: 20 ga. chamber length - Researcher November 3, 2006, 9:18 am   Searching