This is an ORIGINAL WINCHESTER LARGE CALIBER magazine tube made of thick steel - it fits in .30-.30, .38 WCF .38-.40, 38-55, .44 WCF .44-.40 .45, .357 for Winchester lever-action rifles in models 1866, 1873, 1892, 1894 (pre and post 64), 53, 64 and Marlin . These tubes have an OUTSIDE DIAMETER of .645 were blued and have a hole drilled through the Forearm magazine plug screw. There are notches in the tube for the hanger ring pin, so you are able to precisely fit the tube to your rifle. This tube fits the model 1866 (after serial num 14,000) 1873 (after approximately serial number 50,000) and model 1892 in .38 WCF /.38-40 and .44WCF / .44-.40 cal and the model 1894 in ALL cals. This is also the magazine tube Marlin models 1894, 1889, and early 1893, as well as the Sears model 54. The MAGAZINE SPRING that goes in this tube is part number ms73 (it comes with instructions on what length the spring should be cut to in relation to the length of your tube). The lmagazine length is 25 1/4 inch for the 26-inch Sporting Rifle barrels.