KING NITRO Tradename used by Shapleigh Hardware Company of St. Louis, Missouri on shotguns made by Crescent Fire Arms Company and J. Stevens Arms Company
As I saw in other faq`s answered about King Nitro shotguns, they were made by Sears,Roebuck co. We need to find those other answers and correct them. Sears Roebuck never made any guns unless you count those manufactured by their subsidiary company, Meriden Arms from 1905 to 1915. Nitro King was a Sears brand but King Nitro was a trade name distributed by Shapleigh Hardware of St Louis. The guns were made by W.H. Davenport, Iver Johnson, J. Stevens (model 315 double barrel), and unidentified Belgian manufacturers.
You have already identified it as a Shapleigh's King Nitro. Shapleigh Hardware was in St Louis Missouri from the mid 19th century until the middle of the 20th. Their King Nitro guns were manufactured by W.H. Davenport and later by Stevens/Savage.
I was informed that' some Morsel shotguns were made by Navy Arms Co.
Not sure if this is your gun, but Leader Gun Company was a trade name used on shotguns retailed by the Charles Williams Stores, Inc. of New York. Most likely manufacturer would be Crescent Arms, Norwich, CT. "Nitro" would imply proofed for smokeless powder.
American Nitro: Trade name used by H. & D. Folsom Arms Co. on shotguns. Available at http://www.hoosiergunworks.com/catalog/cross_reference.html Hope This Helps.
This site has the information you are looking for about Nikko shotguns: http://www.shotgunworld.com/bbs/viewtopic.php?p=9341
Either them or Marlin (1901 on)
Rossi! They also produce handguns and rifles.
I think Sears did a long time ago....