I find them in business in 1910 in Omaha, they apparently published a catalog for some years, I can't find one on-line that you can look at. Going through Omaha city directories they did employe several people including a person listed as a gun smith.
I found this little outline of Water Clark's father;
Hugh G. Clark was in business in Omaha from 1876 till his death in December, 1892. Beginning in 1876, he was in the general merchandise business until 1884, when he sold out, retaining the agency for various powder and dynamite companies only, which of late years has developed into a large business itself. In connection with a branch, conducted by his son, in Denver, Mr. Clark's business e.'itended as far west as Nevada, and north to Montana. Since Mr. Clark's death the business has been in charge of his son, Walter G. Clark.