In looking for a Marlin model 18 barrel. It would have a overall length of 20" with a dovetail at 12 5/8" from chamber end for the magazine lug. The roll stamp on the barrel should include patent dates of 1889, 1890, 1892, and 1897. Would like a round barrel, but would consider a octagon barrel. Would like good rifling but most important to me is the roll stamp.