Nice barlow, sandmountainslim. Perhaps you could post photos of the mark and pile sides with the blades open? Does the tang stamp have "E.C. Simmons" on it? I am pretty sure it won't. Also, is there a pattern number stamped in the back of the main blade? Your knife was likely made in the 1950's (or 1960's) by ????
Ec Simmons started buying knives from Walden Knife Company in 1874. Simmons bought out controlling interest in Walden in 1902. Simmons adopted the Keen Kutter "wedge and bar" logo in 1905. (Some think it represents a saw tooth) The Keen Kutter marked pocket knives were the top line sold by EC Simmons. Winchester bought out Simmons Hardware in 1922. During the time period from 1902 to 1922, most, and likely all of the knives sold by EC Simmons were manufactured at the Walden Plant in Walden NY. In that regard, I actually would consider EC Simmons Hardware to be both a wholesaler and manufacturer of knives, as they actually owned the plant where their knives were made. E.C. Simmons was very interested in pocket knives from the time he was a boy and encouraged his salesman to push the pocket knife lines.
Winchester bought out Simmons Hardware in 1922 and knife manufacturing was moved from Walden to the Winchester facility in New Haven Connecticut. EC Simmons Hardware and Winchester separated again in 1929, most of the knives were likely made in the Winchester plant during this time period from 1923 to 1929.
During the time period from 1929 to early 1940, knives sold by EC Simmons were made by various manufacturers, most likely most knives were still made by Winchester and Camillus.
In July 1940 Shapleigh Hardware Company purchased EC Simmons Hardware Company. Shapleigh used the Keen Kutter logo, without the E.C. Simmons at the top of the wedge, from that time until 1959, when they closed. During the Shapleigh time, a lot of the knives were made by Camillus, some by Schrade, Utica, possibly Empire and other manufacturers.
In 1960 the Keen Kutter name and logo were purchase by Val Test Distributors. No idea who made their knives? Bear and Sons Cutlery currently makes knives stamped with the Keen Kutter logo, they are easily recognized.
The above information comes from "Keen Kutter Pocket Knives" by Alvin Sellens and also from various avid collectors of Keen Kutters who have posted on here and other forums.
Dan