The .401 Powermag was developed by Herters. It predated the .41 Magnum by three years and there is some speculation that it was the inspiration for the .41 Mag.
I have a couple pages of data and hype on the Powermag but nothing said about the contracter/maker. In 1970 it sold for $59.95 retail, ammo $3.78/50 in all loadings.
Typical Herters gig......a LOT of product for little money.
Herter had excellent rifles, shotguns and handguns commissioned by assorted major houses all over the world. I think Sauer was the contractor for the .401.
George Herter seemed to care. He was actually interested in huntin, fishin, adventurin, packin, safaris, shootin, gunsmithin etc etc. He wrote some of the hokiest descriptions ever, yet his products worked.
The catalogs are very entertaining reading. But the customer generally got a lot of product for the buck.
To prove a point.....he nailed a leopard with one of his .401s. One shot at very close range, just above the eye line.
A fair amount of Herter's business was in mailorder firearms. The GCA of 68 hurt a lot. Then when papa George Herter died, not long after so went the company.
Sam
